Carbazole Derivative and Method for Producing the Same

ABSTRACT

To provide a method for producing a wide variety of carbazole derivatives which have a simple and uncomplicated process and in which variations in the yield, purity, etc. of a desired substance which are caused by an aryl group introduced is reduced as much as possible. A method for producing a carbazole derivative represented by General Formula (1) is provided, in which 9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole having an active site at the 3-position of the carbazole skeleton and an aromatic compound having an active site are coupled. 
     
       
         
         
             
             
         
       
     
     In the formula, Ar 1  represents an aryl group with 6 to 13 carbon atoms in a ring, and Ar 1  may have a substituent.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for producing carbazolederivatives. Specifically, the present invention relates to a method forproducing carbazole derivatives which each have a wide band gap and aregood bipolar substances with a high electron-transport property and ahigh hole-transport property and suitable for use in light-emittingelements.

2. Description of the Related Art

A carbazole derivative represented by General Formula K1 below whichcovers carbazole derivatives that are desired substances of anembodiment of the present invention and a carbazole derivativerepresented by General Formula (1) below which is a desired substance ofan embodiment of the present invention are well-known substances. It isalso well known that each substance has a large band gap, can emit lightof an extremely short wavelength, and can exhibit blue light emissionwith high color purity (see Patent Documents 1 and 2). Further, highelectrochemical stability of these derivatives and also methods forproducing them are naturally known (see Patent Documents 1 and 2).

As the known method for producing the derivative represented by GeneralFormula (I), there are two methods, which are described in PatentDocuments 1 and 2. The production method described in Patent Document 1is referred to as a first known method. The first known method will bedetailed hereinbelow and consists of three steps: Reaction Formulae(K-1), (K-2), and (K-3).

In accordance with the first known method, 9H-carbazole (Compound K1) isfirst halogenated to give a carbazole derivative (Compound K2) (ReactionFormula (K-1)). In Reaction Formula (K-1), X² represents a halogen,preferably iodine or bromine. When bromination is carried out inReaction Formula (K-1), examples of brominating agents that can be usedinclude bromine, N-bromosuccinimide, and the like. Examples of solventsthat can be used in this case include halogen-based solvents such aschloroform and carbon tetrachloride. When N-bromosuccinimide is used asthe brominating agent, ethyl acetate, tetrahydrofuran,dimethylformamide, acetic acid, water, or the like can be used as thesolvent.

When iodination is carried out in Reaction Formula (K-1), examples ofiodinating agents that can be used include N-iodosuccinimide,1,3-diiodo-5,5-dimethylimidazolidine-2,4-dione (abbreviation: DIH),2,4,6,8-tetraiodo-2,4,6,8-tetraazabicyclo[3,3,0]octane-3,7-dione,2-iodo-2,4,6,8-tetraazabicyclo[3,3,0]octane-3,7-dione, and the like.

Further, examples of solvents that can be used alone or in combinationfor iodination with such an iodinating agent include aromatichydrocarbons such as benzene, toluene, and xylene; ethers such as1,2-dimethoxyethane, diethyl ether, methyl-t-butyl ether,tetrahydrofuran, and dioxane; saturated hydrocarbons such as pentane,hexane, heptane, octane, and cyclohexane; halogens such asdichloromethane, chloroform, carbon tetrachloride, 1,2-dichloroethane,and 1,1,1-trichloroethane; nitriles such as acetonitrile andbenzonitrile; esters such as ethyl acetate, methyl acetate, and butylacetate; acetic acid (glacial acetic acid); water; and the like. Whenwater is used, water is preferably mixed with an organic solvent.Furthermore, in this reaction, acid such as sulfuric acid or acetic acidis preferably used at the same time.

Next, the carbazole derivative obtained (Compound K2) and aryl boronicacid [Compound K3 (corresponding to “Compound 3” of the presentinvention)] are coupled according to a Suzuki-Miyaura reaction using apalladium catalyst, whereby 3-aryl-9H-carbazole (Compound K4) isobtained (Reaction Formula (K-2)). In Reaction Formula (K-2), X²represents a halogen, preferably iodine or bromine. Alternatively, inReaction Formula (K-2), a compound in which X² is a triflate group maybe used. Note that an organoboron compound represented by Compound K3 isreferred to as aryl boronic acid when R¹⁰¹ and R¹⁰² independentlyrepresent hydrogen.

In Reaction Formula (K-2), Ar¹ represents an aryl group with 6 to 13carbon atoms which may have a substituent. Examples of palladiumcatalysts that can be used in this reaction formula includepalladium(II) acetate, tetrakis(triphenylphosphine)palladium(0), and thelike. Examples of ligands of the palladium catalyst which can be used inReaction Formula (K-2) include tri(ortho-tolyl)phosphine,triphenylphosphine, tricyclohexylphosphine, and the like.

Examples of bases that can be used in Reaction Formula (K-2) includeorganic bases such as sodium tert-butoxide, inorganic bases such aspotassium carbonate, and the like. Examples of solvents that can be usedin Reaction Formula (K-2) include a mixed solvent of toluene and water,a mixed solvent of toluene, an alcohol such as ethanol, and water, amixed solvent of xylene and water, a mixed solvent of xylene, an alcoholsuch as ethanol, and water, a mixed solvent of benzene and water, amixed solvent of benzene, an alcohol such as ethanol, and water, a mixedsolvent of an ether such as ethyleneglycoldimethylether and water, andthe like. Note that use of a mixed solvent of toluene and water or amixed solvent of toluene, ethanol, and water is more preferable.

In Reaction Formula (K-3) which is the last reaction step of the firstknown method, an anthracene derivative (Compound K5) and the carbazolederivative (Compound K4) are coupled according to a Hartwig-Buchwaldreaction using a palladium catalyst or an Ullmann reaction using copperor a copper compound. Thus, a carbazole derivative represented byGeneral Formula (I) which is the same desired substance as a productionmethod of an embodiment of the present invention is obtained.

In Reaction Formula (K-3), X³ represents a halogen or a triflate group;when X³ is a halogen, it is preferably iodine, bromine, or chlorine. Inthis reaction formula, Ar¹ represents an aryl group with 6 to 13 carbonatoms which may have a substituent. Examples of palladium catalysts thatcan be used for a Hartwig-Buchwald reaction in Reaction Formula (K-3)include bis(dibenzylideneacetone)palladium(0), palladium(II) acetate,and the like.

Examples of ligands of the palladium catalyst which can be used inReaction Formula (K-3) include tri(tert-butyl)phosphine,tri(n-hexyl)phosphine, tricyclohexylphosphine, and the like. Examples ofbases that can be used include organic bases such as sodiumtert-butoxide, inorganic bases such as potassium carbonate, and thelike. Further, examples of solvents that can be used include toluene,xylene, benzene, tetrahydrofuran, and the like.

In Reaction Formula (K-3), an Ullmann reaction can be carried outinstead of a Hartwig-Buchwald reaction, as described above, in whichcase copper or a copper compound is used instead of a palladiumcatalyst. In this case, R¹¹¹ and R¹¹² independently represent a halogen,an acetyl group, or the like; as the halogen, there are chlorine,bromine, and iodine. Further, use of copper(I) iodide in which R¹¹¹ isiodine or copper(II) acetate in which R¹¹² is an acetyl group ispreferable. As the base that can be used in this case, an inorganic basesuch as potassium carbonate is given.

Further, examples of solvents that can be used in the above reactioninclude 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)pyrimidinone (DMPU),toluene, xylene, benzene, and the like. In an Ullmann reaction, since areaction temperature of 100° C. or more enables the desired substance ina shorter time and a higher yield, DMPU or xylene, which has a highboiling point, is preferably used. In addition, since the reactiontemperature is more preferably 150° C. or more, use of DMPU ispreferred.

The first known method is as described above. A second known method is aproduction method described in Patent Document 2 and consists of threesteps: Reaction Formulae (K-4), (K-5), and (K-6), as specificallydescribed hereinbelow. Note that since Compound K4 which is a startingmaterial in Reaction Formula (K-4) is obtained through two reactionsteps: Reaction Formulae (K-1) and (K-2), the second known methodincludes another two reaction steps in a strict sense.

The carbazole derivative synthesized by the first known method (CompoundK4) and para-dihalogenated benzene (Compound K6) are coupled accordingto a Hartwig-Buchwald reaction using a palladium catalyst or an Ullmannreaction using copper or a copper compound, whereby a carbazolederivative (Compound K7) can be obtained (Reaction Formula (K-4)). InReaction Formula (K-4), X⁴ and X⁵ independently represent a halogen or atriflate group; when X⁴ and X⁵ independently represent a halogen, it ispreferably iodine, bromine, or chlorine. In addition, X⁴ and X⁵ may bethe same or different from each other. In Reaction Formula (K-4), Ar¹represents an aryl group with 6 to 13 carbon atoms which may have asubstituent.

For a Hartwig-Buchwald reaction in Reaction Formula (K-4), examples ofpalladium catalysts that can be used includebis(dibenzylideneacetone)palladium(0), palladium(II) acetate, and thelike. Examples of ligands of the palladium catalyst which can be usedinclude tri(tert-butyl)phosphine, tri(n-hexyl)phosphine,tricyclohexylphosphine, and the like. Examples of bases that can be usedinclude organic bases such as sodium tert-butoxide, inorganic bases suchas potassium carbonate, and the like. Further, examples of solvents thatcan be used include toluene, xylene, benzene, tetrahydrofuran, and thelike.

In Reaction Formula (K-4), an Ullmann reaction can be performed insteadof a Hartwig-Buchwald reaction, as described above, in which case copperor a copper compound is used instead of a palladium catalyst. In thiscase, R¹¹¹ and R¹¹² independently represent a halogen, an acetyl group,or the like; as the halogen, there are chlorine, bromine, or iodine.Further, use of copper(I) iodide in which R¹¹¹ is iodine or copper(II)acetate in which R¹¹² is an acetyl group is preferable. Instead of acopper compound, copper can alternatively be used.

Furthermore, as a base that can be used in the above reaction formula,an inorganic base such as potassium carbonate is given. Examples ofsolvents that can be used include1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)pyrimidinone (DMPU), toluene,xylene, benzene, and the like. In an Ullmann reaction, since a reactiontemperature of 100° C. or more enables the desired substance in ashorter time and a higher yield, DMPU or xylene, which has a highboiling point, is preferably used. In addition, since the reactiontemperature is more preferably 150° C. or more, use of DMPU ispreferred.

Next, the carbazole derivative obtained (Compound K7) undergoes boronoxidation using an alkyl lithium reagent and a boron reagent, whereby aboronic acid body (Compound K8) of the carbazole derivative is obtained(Reaction Formula (K-5)). In Reaction Formula (K-5), X⁵ represents ahalogen or a triflate group; as the halogen, it is preferably iodine,bromine, or chlorine, and Ar¹ represents an aryl group with 6 to 13carbon atoms which may have a substituent. Further, the boronic acid ofCompound K8 may be used in the subsequent reaction after being protectedwith ethylene glycol or pinacol.

In Reaction Formula (K-5), R⁵⁰ represents an alkyl group with 1 to 6carbon atoms, and R⁵¹ represents an alkyl group with 1 to 6 carbonatoms. Examples of solvents that can be used include ether-basedsolvents such as diethyl ether, tetrahydrofuran (THF), and cyclopentylmethyl ether. Further, examples of alkyl lithium reagents includen-butyllithium in which R⁵⁰ is an n-butyl group, t-butyllithium in whichR⁵⁰ is a t-butyl group, and methyllithium in which R⁵⁰ is a methylgroup, and the like. Furthermore, examples of boron reagents includetrimethyl borate in which R⁵¹ is a methyl group, triisopropyl borate inwhich R⁵¹ is an isopropyl group, and the like.

Lastly, the boronic acid body (Compound K8) of the carbazole derivativeand an anthracene derivative (Compound K9) are coupled according to aSuzuki-Miyaura coupling reaction using a palladium catalyst, whereby thedesired substance represented by General Formula (I) is obtained(Reaction Formula (K-6)). In Reaction Formula (K-6), X⁶ represents ahalogen or a triflate group; when X⁶ is a halogen, it is preferablyiodine, bromine, or chlorine.

In Reaction Formula (K-6), Ar¹ represents an aryl group with 6 to 13carbon atoms which may have a substituent. Examples of palladiumcatalysts that can be used include palladium(II) acetate,tetrakis(triphenylphosphine)palladium(0), and the like. Examples ofligands of the palladium catalyst which can be used in this case includetri(ortho-tolyl)phosphine, triphenylphosphine, tricyclohexylphosphine,and the like. Examples of bases that can be used in this reactionformula include organic bases such as sodium tert-butoxide, inorganicbases such as potassium carbonate, and the like

Further, examples of solvents that can be used in the above reactioninclude a mixed solvent of toluene and water, a mixed solvent oftoluene, an alcohol such as ethanol, and water, a mixed solvent ofxylene and water, a mixed solvent of xylene, an alcohol such as ethanol,and water, a mixed solvent of benzene and water, a mixed solvent ofbenzene, an alcohol such as ethanol, and water, a mixed solvent of anether such as ethyleneglycoldimethylether and water, and the like.Further, use of a mixed solvent of toluene and water or a mixed solventof toluene, ethanol, and water is more preferable. Note that instead ofCompound K8, an organoboron compound obtained by protecting the boronicacid of Compound K8 with ethylene glycol or pinacol may be used.

As described above, a compound represented by General Formula (I) whichis a desired substance of a production method of the present inventionis a known substance, and the two methods for producing the compound isalso known. Further, the compound represented by General Formula (I) hasa structure in which an anthracene skeleton and a carbazole skeleton arebonded and an aryl group is bonded to the 3-position of the carbazoleskeleton.

In each known production method, the formation processes is not simpledue to a number of reaction steps up to formation of a desiredsubstance. Further, any of a variety of aryl groups can be applied to anaryl group (Ar¹) in a derivative represented by General Formula (I)which is a desired substance of both a production method of the presentinvention and the known production methods, and a wide variety ofcarbazole derivatives can be produced by these methods. However, sincethe known production methods involve, before an anthracene skeleton anda carbazole skeleton are bonded, the introduction of the aryl group thatis to be bonded to the 3-position of the carbazole skeleton, it can besaid that such methods are not effective in producing a wide variety ofcarbazole derivatives.

In other words, in the known production methods, because of theintroduction of an aryl group to the 3-position of the carbazoleskeleton before the anthracene skeleton and the carbazole skeleton arebonded, the bonding reaction of the both skeletons occurs after theintroduction. Accordingly, in the first known method, there is a problemin that what kind of aryl group is introduced affects the reaction inwhich the aryl group is introduced and the following reaction in whichthe both skeletons are bonded, so that the yield, purity, etc. of adesired substance varies depending on the aryl group introduced.

Moreover, in the second known method, since Compound K4 which is thestarting material in Reaction Formula (K-4) which is the first step iscarbazole in which an aryl group is introduced, the carbazole undergoesthree steps of reactions: Reaction Formulae (K-4), (K-5), and (K-6).Therefore, in each step, the aryl group substituted affects progressionof the reaction. Accordingly, the yield, purity, etc. of a desiredsubstance varies depending on the aryl group introduced to the startingmaterial.

REFERENCES Patent Documents

-   [Patent Document 1] Japanese Published Patent Application No.    2007-39431-   [Patent Document 2] Japanese Published Patent Application No.    2008-81497

SUMMARY OF THE INVENTION

As described above, in the above-described known production methods, theformation process is not simple, and what kind of aryl group isintroduced significantly affects the yield, purity, etc. of a desiredsubstance in production of a wide variety of carbazole derivatives.Through detailed studies, the present inventors have found a novelmethod for producing carbazole derivatives in which such a problem isreduced. Specifically, an object of the present invention is to providea method for producing a wide variety of carbazole derivatives whichhave a simple and uncomplicated process and in which variations in theyield, purity, etc. of a desired substance which depend on an aryl groupintroduced are reduced as much as possible.

An embodiment of the present invention provides a method for producing acarbazole derivative represented by General Formula (I), in which9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole having an active site atthe 3-position of the carbazole skeleton and an aromatic compound havingan active site are coupled. Also, an embodiment of the present inventionincludes 9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole having an activesite at the 3-position of the carbazole skeleton, and a productionmethod thereof.

In the formula, Ar¹ represents an aryl group with 6 to 13 carbon atomsin a ring. In addition, Ar¹ may have a substituent.

Further, a preferable embodiment of the present invention is a methodfor producing a carbazole derivative represented by General Formula(1a), in which 9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole having anactive site at the 3-position of the carbazole skeleton and an aromaticcompound having an active site which is represented by Compound (A1) arecoupled using a metal catalyst.

In the formula, X represents an active site, and R¹ to R⁵ independentlyrepresent hydrogen, an alkyl group with 1 to 4 carbon atoms, or an arylgroup with 6 to 13 carbon atoms in a ring which may have a substituent.

In the formula, R¹ to R⁵ independently represent hydrogen, an alkylgroup with 1 to 4 carbon atoms, or an aryl group with 6 to 13 carbonatoms in a ring which may have a substituent.

Further, a more preferable embodiment of the present invention is amethod for producing a carbazole derivative represented by GeneralFormula (1b), in which 9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazolehaving an active site at the 3-position of the carbazole skeleton and anorganoboron compound which is represented by Compound (A2) are coupledusing a palladium catalyst.

In the formula, R¹⁰¹ and R¹⁰² independently represent hydrogen or analkyl group having 1 to 6 carbon atoms and may be bonded to form a ringstructure. Note that an organoboron compound represented by Compound(A2) is referred to as aryl boronic acid when R¹⁰¹ and R¹⁰²independently represent hydrogen in General Formula (1b).

According to the present invention, the aryl group (Ar¹) can havedifferent variations through one reaction step, whereby a wide varietyof carbazole derivatives can be produced. Thus, the present inventionprovides an excellent method in which a variety of carbazole derivativesare produced by a simple and uncomplicated process. Further, unlikeknown methods, the present invention does not require two or morereaction steps after a functional group of the aryl group (Ar¹) havingdifferent variations is introduced to the 3-position of the carbazoleskeleton in production of a variety of carbazole derivatives.Accordingly, a reduction in the yield, purity, etc. of a desiredsubstance which is caused by the aryl group introduced to the carbazolegroup can be suppressed as much as possible.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A to 1C each illustrate a light-emitting element according to anembodiment of the present invention.

FIG. 2 illustrates a light-emitting element according to an embodimentof the present invention.

FIGS. 3A and 3B each illustrate a light-emitting element according to anembodiment of the present invention.

FIG. 4 illustrates a light-emitting element according to an embodimentof the present invention.

FIGS. 5A and 5B illustrate a light-emitting device according to anembodiment of the present invention.

FIGS. 6A and 6B illustrate a light-emitting device according to anembodiment of the present invention.

FIGS. 7A to 7D each illustrate an electronic device according to anembodiment of the present invention.

FIG. 8 illustrates an electronic device according to an embodiment ofthe present invention.

FIG. 9 illustrates a lighting apparatus according to an embodiment ofthe present invention.

FIG. 10 illustrates a lighting apparatus according to an embodiment ofthe present invention.

FIGS. 11A and 11B show ¹H NMR charts of CzPAP.

FIG. 12 shows an absorption spectrum of a toluene solution of CzPAP.

FIG. 13 shows an absorption spectrum of a thin film of CzPAP.

FIG. 14 shows an emission spectrum of a toluene solution of CzPAP.

FIG. 15 shows an emission spectrum of a thin film of CzPAP.

FIG. 16 shows CV measurement results of CzPAP.

FIG. 17 shows CV measurement results of CzPAP.

FIGS. 18A and 18B show ¹H NMR charts of CzPAαNP.

FIGS. 19A and 19B show ¹H NMR charts of CzPAαN.

FIGS. 20A and 20B show ¹H NMR charts of CzPAfβN.

FIGS. 21A and 21B show ¹H NMR charts of CzPApB.

FIGS. 22A and 22B show ¹H NMR charts of CzPAoB.

FIGS. 23A and 23B show ¹H NMR charts of CzPAFL.

FIG. 24 illustrates an example of formation of light-emitting elementsaccording to an embodiment of the present invention.

FIG. 25 shows current density vs. luminance characteristics ofLight-Emitting Element 1.

FIG. 26 shows voltage vs. luminance characteristics of Light-EmittingElement 1.

FIG. 27 shows luminance vs. current efficiency characteristics ofLight-Emitting Element 1.

FIG. 28 shows an emission spectrum of Light-Emitting Element 1.

FIG. 29 shows current density vs. luminance characteristics ofLight-Emitting Element 2.

FIG. 30 shows voltage vs. luminance characteristics of Light-EmittingElement 2.

FIG. 31 shows luminance vs. current efficiency characteristics ofLight-Emitting Element 2.

FIG. 32 shows an emission spectrum of Light-Emitting Element 2.

FIG. 33 shows results obtained by reliability testing of Light-EmittingElement 1.

FIG. 34 shows results obtained by reliability testing of Light-EmittingElement 2.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, various embodiments of the present invention which includethe best mode for implementing the present invention will be describedin detail with reference to the accompanying drawings as necessary. Notethat the present invention is not limited to the description below.Thus, it is easily understood by those skilled in the art that the modesand details of the present invention can be easily modified in variousways without departing from the spirit and scope of the presentinvention. Further, applications of the substances that are desiredsubstances produced by a production method of the present invention,etc. will also be detailed below.

An embodiment of the present invention is a method for producing acarbazole derivative represented by General Formula (I), in which9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole having an active site atthe 3-position of the carbazole skeleton and an aromatic compound havingan active site are coupled, as described above. Note that the termaromatic compound in this specification does not cover a heterocycliccompound.

An embodiment of the present invention is a method for producing acarbazole derivative represented by the above General Formula (I), inwhich 9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole having an activesite at the 3-position of the carbazole skeleton and an aromaticcompound having an active site are coupled, as described above. A stepof forming 9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole having anactive site at the 3-position which is an early step of the productionmethod and the subsequent coupling step are illustrated in the followingReaction Formulae 1 and 2.

Note that X⁷ of Compound 2 represents an active site. Examples of theactive site X⁷ include halogens, boronic acid, organoboron compounds,organotin compounds, trifluoromethanesulfonate (triflate), Grignardreagents, organic mercury compounds, thiocyanate, organozinec compounds,organoaluminum compounds, organozirconium compounds, and the like.

Note that X⁸ of Compound 3 represents an active site. Examples of theactive site X⁸ include halogens, boronic acid, organoboron compounds,organotin compounds, trifluoromethanesulfonate (triflate), Grignardreagents, organic mercury compounds, thiocyanate, organozinc compounds,organoaluminum compounds, organozirconium compounds, and the like. InGeneral Formula (I), Ar¹ represents an aryl group with 6 to 13 carbonatoms in a ring. In addition, Ar¹ may have a substituent.

Hereinafter, the substituent Ar¹ which is to be introduced to acarbazole derivative represented by General Formula (I) will be furtherdetailed. As examples of the aryl group of this Ar¹, there are a phenylgroup, a naphthyl group, a fluorenyl group, and the like. When the arylgroup has a substituent, as examples of the substituent, there are analkyl group with 1 to 4 carbon atoms, a haloalkyl group with one carbonatom, a phenyl group, a naphthyl group, a fluorenyl group, and the like.Note that when Ar¹ has a substituent, substituents may be bonded to forma ring, in which case a spiro ring is included in the ring structure.Further, carbon atoms in the spiro ring of this case are in a ring.

As specific structures of the aryl group of Ar¹, there are substituents(S-1) to (S-24) below, and the like, for example. Among thesesubstituents, the substituent (S-1) is a specific example where the arylgroup is a phenyl group, and the substituents (S-4) to (S-16) are each aspecific example where the phenyl group further has a substituent.Further, the substituents (S-2) and (S-3) are each a specific examplewhere the aryl group is a naphthyl group. The substituents (S-17) to(S-19) are each a specific example where the aryl group is a fluorenylgroup and has a substituent. Note that the substituent (S-18) is aspecific example where the substituents are bonded to form a spiro ring.

A method for producing carbazole derivatives according to an embodimentof the present invention is a method for producing a carbazolederivative represented by General Formula (1) which is a desiredsubstance, in which a coupling reaction of9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole having an active site atthe 3-position of the carbazole skeleton and an aryl group having anactive site is carried out as illustrated in Reaction Formula 2 using ametal catalyst such as a palladium catalyst or a nickel catalyst. As thecoupling reaction, Suzuki-Miyaura coupling, Migita-Kosugi-Stillecoupling, Kumada-Tamao coupling, Negishi coupling, or the like can beused. The metal catalyst may be a metal such as copper or iron or ametal compound such as copper(I) iodide.

Further, a preferable embodiment of the present invention is thefollowing method, i.e., the method for producing a carbazole derivativerepresented by the above-described General Formula (1a), in which9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole having an active site atthe 3-position of the carbazole skeleton and an aryl group having anactive site which is represented by Compound (A1) are coupled using ametal catalyst. As the metal catalyst used in the reaction, a metalcatalyst such as a palladium catalyst or a nickel catalyst can be given.In addition, the metal catalyst may be a metal such as copper or iron ora metal compound such as copper(I) iodide.

Further, a more preferable embodiment of the present invention is thefollowing method, i.e., the method for producing a carbazole derivativerepresented by the above-described General Formula (1b), in which9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole having an active site atthe 3-position of the carbazole skeleton and an organoboron compoundwhich is represented by Compound (A2) are coupled using a palladiumcatalyst. Note that an organoboron compound represented by Compound (A2)is referred to as aryl boronic acid when R¹⁰¹ and R¹⁰² independentlyrepresent hydrogen.

Compounds produced by a production method of the present invention arespecifically represented by Structural Formulae 1 to 31, for example.The compound names of some of those compounds are3-phenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation:CzPAP, the compound represented by Structural Formula 1) and3-[4-(1-naphthyl)phenyl]-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole(abbreviation: CzPAaNP, the compound represented by Structural Formula2).

Embodiment 1

An example of a production method of the present invention will bedetailed hereinbelow. According to the production method which is anembodiment of the present invention,9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole having an active site atthe 3-position of the carbazole skeleton and an aromatic compound havingan active site are coupled as described above.

In Embodiment 1, an example in which Suzuki-Miyaura coupling is carriedout in the coupling reaction of the above Reaction Formula 2 will bedescribed. When Suzuki-Miyaura coupling is carried out in the couplingreaction of the above Reaction Formula 2, it is preferable that X⁷ ofCompound 2 be a halogen or triflate and that X⁸ of Compound 3 be boronicacid or an organoboron compound. Alternatively, it is preferable that X⁷of Compound 2 be boronic acid or an organoboron compound and that X⁸ bea halogen or triflate. Moreover, a palladium catalyst is preferablyused. In Embodiment 1, an example in which X⁷ of Compound 2 is a halogenor triflate and X⁸ of Compound 3 is boronic acid or an organoboroncompound will be described. Note that as a coupling reaction of theproduction method of Embodiment 1, Migita-Kosugi-Stille coupling,Kumada-Tamao coupling, Negishi coupling, or the like can be used.

As described above, the production method also involves: the step forforming 9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole having an activesite at the 3-position which is an early step of the production method;and the subsequent coupling step. These reaction steps are illustratedin Reaction Formulae M1 and M2 below. Specifically, as the first step,according to Reaction Formula M1,9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (Compound 1,abbreviation: CzPA) is directly halogenated so that Compound M1 in whichthe 3-position of the carbazole skeleton of CzPA is halogenated isobtained.

In Reaction Formula M1, X¹ represents a halogen, preferably iodine orbromine. When bromination is carried out in this reaction, examples ofbrominating agents that can be used include bromine, N-bromosuccinimide,and the like. Examples of solvents that can be used for brominationusing bromine include, but not limited to, halogen-based solvents suchas chloroform and carbon tetrachloride. Examples of solvents that can beused for bromination using N-bromosuccinimide include ethyl acetate,tetrahydrofuran, dimethylformamide, acetic acid, water, and the like.

When iodination is carried out in Reaction Formula M1, examples ofiodinating agents that can be used include N-iodosuccinimide,1,3-diiodo-5,5-dimethylimidazolidine-2,4-dione (abbreviation: DIH),2,4,6,8-tetraiodo-2,4,6,8-tetraazabicyclo[3,3,0]octane-3,7-dione,2-iodo-2,4,6,8-tetraazabicyclo[3,3,0]octane-3,7-dione, and the like.

Further, examples of solvents that can be used alone or in combinationfor iodination using such an iodinating agent include aromatichydrocarbons such as benzene, toluene, and xylene; ethers such as1,2-dimethoxyethane, diethyl ether, methyl-t-butyl ether,tetrahydrofuran, and dioxane; saturated hydrocarbons such as pentane,hexane, heptane, octane, and cyclohexane; halogens such asdichloromethane, chloroform, carbon tetrachloride, 1,2-dichloroethane,and 1,1,1-trichloroethane; nitriles such as acetonitrile andbenzonitrile; esters such as ethyl acetate, methyl acetate, and butylacetate; acetic acid (glacial acetic acid); water; and the like.

In the above case, when water is used, water is preferably mixed with anorganic solvent. Further, in this reaction, acid such as sulfuric acidor acetic acid is preferably used at the same time, and the acid thatcan be used is not limited to these examples. Note that a method otherthan halogenation illustrated in Reaction Formula M1 may be used, and acompound in which a triflate group is substituted at the 3-position ofthe carbazole skeleton of CzPA may be synthesized.

Next, the reaction of Reaction Formula M2 which is a reaction of thesecond step is carried out. In this reaction, Compound M1 in which the3-position of the carbazole skeleton of CzPA is halogenated and anorganoboron compound which is Compound M2 are coupled according to aSuzuki-Miyaura reaction using a palladium catalyst, whereby a CzPAderivative represented by General Formula (I) which is the desiredsubstance is obtained. Note that an organoboron compound represented byCompound M2 is referred to as aryl boronic acid when R¹⁰¹ and R¹⁰²independently represent hydrogen.

In Reaction Formula M2, X¹ represents a halogen, preferably iodine orbromine. Alternatively, in this reaction formula, a compound in which X¹is a triflate group may be used. Further, in this reaction formula, Ar¹represents an aryl group with 6 to 13 carbon atoms which may have asubstituent. Substituents may be bonded to form a ring, and a spiro ringis included in the ring structure. Furthermore, in this reactionformula, R¹⁰¹ and R¹⁰² independently represent hydrogen or an alkylgroup having 1 to 6 carbon atoms and may be bonded to form a ringstructure.

Examples of palladium catalysts that can be used in Reaction Formula M2include palladium(II) acetate, tetrakis(triphenylphosphine)palladium(0),and the like. Examples of ligands of the palladium catalyst which can beused here include tri(ortho-tolyl)phosphine, triphenylphosphine,tricyclohexylphosphine, and the like. Examples of bases that can be usedin this reaction formula include organic bases such as sodiumtert-butoxide, inorganic bases such as potassium carbonate, and thelike.

Examples of solvents that can be used in Reaction Formula M2 include amixed solvent of toluene and water; a mixed solvent of toluene, analcohol such as ethanol, and water; a mixed solvent of xylene and water;a mixed solvent of xylene, an alcohol such as ethanol, and water; amixed solvent of benzene and water; a mixed solvent of benzene, analcohol such as ethanol, and water; a mixed solvent of an ether such asethyleneglycoldimethylether and water; and the like. Use of a mixedsolvent of toluene and water or a mixed solvent of toluene, ethanol, andwater is more preferable.

Embodiment 2

An example of a light-emitting element formed using any of the carbazolederivatives produced by a production method of the present inventionwill be described below with reference to FIG. 1A. In thislight-emitting element, an EL layer which includes at least a layerincluding a light-emitting substance (also referred to as alight-emitting layer) is interposed between a pair of electrodes. The ELlayer may also have a plurality of layers in addition to the layerincluding a light-emitting substance. The plurality of layers are astack of layers each including a substance with a high carrier-injectproperty or a substance with a high carrier-transport property such thata light-emitting region is formed in a region away from the electrodes,i.e., such that carriers recombine in an area away from the electrodes.

In this specification, the layer including a substance with a highcarrier-inject property or a substance with a high carrier-transportproperty is also referred to as a functional layer which, for example,functions to inject or transport carriers. As the functional layer, itis possible to use any of the following layers: a layer including asubstance with a high hole-inject property (also referred to as ahole-inject layer), a layer including a substance with a highhole-transport property (also referred to as a hole-transport layer), alayer including a substance with a high electron-inject property (alsoreferred to as an electron-inject layer), a layer including a substancewith a high electron-transport property (also referred to as anelectron-transport layer), and the like.

In the light-emitting element of Embodiment 2 which are illustrated ineach of FIGS. 1A to 1C, an EL layer 108 is provided between a firstelectrode 102 and a second electrode 107. The EL layer 108 has a firstlayer 103, a second layer 104, a third layer 105, and a fourth layer106. The light-emitting element in each of FIGS. 1A to 1C includes thefirst electrode 102 over a substrate 101, a stack of the first layer103, the second layer 104, the third layer 105, and the fourth layer 106in that order over the first electrode 102, and a second electrode 107provided thereover. Note that it is assumed that the first electrode 102functions as an anode and the second electrode 107 functions as acathode in Embodiment 2.

The substrate 101 is used as a support of the light-emitting element.For the substrate 101, glass, quartz, plastic, or the like may be used,for example. Alternatively, a flexible substrate can be used. Theflexible substrate means a substrate that can be bent, such as a plasticsubstrate made of polycarbonate, polyarylate, polyacrylate, or polyethersulfone, for example. Still alternatively, a film (of polypropylene,polyester, vinyl, polyvinyl fluoride, vinyl chloride, or the like) or afilm formed by evaporation of an inorganic material can be used. Notethat any material other than these examples may be used as long as thematerial functions as a support of the light-emitting element during theprocess of forming the light-emitting element.

Preferably, the first electrode 102 is formed using a metal, an alloy, aconductive compound, a mixture thereof, or the like having a high workfunction (specifically, 4.0 eV or more). For example, there are ITO(indium oxide-tin oxide), indium oxide-tin oxide containing silicon orsilicon oxide, IZO (indium oxide-zinc oxide), IWZO (indium oxidecontaining tungsten oxide and zinc oxide), and the like. Films of suchconductive metal oxides are normally formed by sputtering, but may alsobe formed by applying a sol-gel method or the like.

For example, a film of IZO (indium oxide-zinc oxide) can be formed by asputtering method using a target in which zinc oxide is added to indiumoxide at 1 to 20 wt %. In addition, a film of IWZO (indium oxidecontaining tungsten oxide and zinc oxide) can be formed by a sputteringmethod using a target in which tungsten oxide and zinc oxide are addedto indium oxide at 0.5 to 5 wt % and 0.1 to 1 wt % respectively.Further, there are gold (Au), platinum (Pt), nickel (Ni), tungsten (W),chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu),palladium (Pd), a nitride of a metal material (e.g., titanium nitride),and the like.

The first layer 103 is a layer including a substance with a highhole-inject property, and molybdenum oxide, vanadium oxide, rutheniumoxide, tungsten oxide, manganese oxide, or the like can be used.Alternatively, the first layer 103 can be formed using any of thefollowing materials: phthalocyanine compounds such as phthalocyanine(abbreviation: H₂Pc) and copper phthalocyanine (CuPc), aromatic aminecompounds such as4,4′-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation:DPAB) and4,4′-bis(N-{4-[N-(3-methylphenyl)-N-phenylamino]phenyl}-N-phenylamino)biphenyl(abbreviation: DNTPD), high molecular compounds such aspoly(3,4-ethylenedioxythiophene)/poly(styrenesulfonic acid) (PEDOT/PSS),and the like.

Alternatively, for the first layer 103, a composite material formed bycomposing an organic compound and an inorganic compound can be used. Acomposite material containing an organic compound and an inorganiccompound having an electron-accepting property with respect to theorganic compound, in particular, has an excellent hole-inject propertyand hole-transport property because, in this material, electrons aretransported between the organic compound and the inorganic compound toincrease the carrier density. When the composite material formed bycomposing an organic compound and an inorganic compound is used for thefirst layer 103 as described above, the first layer 103 can achieve anohmic contact with the first electrode 102; therefore, a material of thefirst electrode can be selected regardless of the work function.

The inorganic compound used for the composite material is preferably anoxide of a transition metal. Moreover, oxides of metals of Groups 4 to 8of the periodic table can be given. Specifically, use of vanadium oxide,niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide,tungsten oxide, manganese oxide, or rhenium oxide is preferable becauseof their high electron-accepting properties. In particular, use ofmolybdenum oxide is more preferable because of its stability in theatmosphere, a low hygroscopic property, and easily handling.

As the organic compound used for the composite material, any of avariety of compounds such as aromatic amine compounds, carbazolederivatives, aromatic hydrocarbons, or high molecular compounds(oligomers, dendrimers, polymers, etc.) can be used. Note that theorganic compound used for the composite material preferably has a highhole-transport property. Specifically, a substance having a holemobility of 10⁻⁶ cm²/Vs or more is preferably used. Further, any othersubstance may be used as long as it is a substance in which thehole-transport property is higher than the electron-transport property.Hereinbelow, organic compounds that can be used for the compositematerial are specifically given.

Examples of the aromatic amine compounds includeN,N′-di(p-tolyl)-N,N-diphenyl-p-phenylenediamine (abbreviation: DTDPPA),4,4′-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation:DPAB),4,4′-bis(N-{4-[N-(3-methylphenyl)-N-phenylamino]phenyl}-N-phenylamino)biphenyl(abbreviation: DNTPD),1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene(abbreviation: DPA3B), and the like.

Specific examples of the carbazole derivatives that can be used for thecomposite material include3-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole(abbreviation: PCzPCA1);3,6-bis[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole(abbreviation: PCzPCA2),3-[N-(1-naphtyl)-N-(9-phenylcarbazol-3-yl)amino]-9-phenylcarbazole(abbreviation: PCzPCN1), and the like.

Alternatively, 4,4′-di(N-carbazolyl)biphenyl (abbreviation: CBP),1,3,5-tris[4-(N-carbazolyl)phenyl]benzene (abbreviation: TCPB),9-[4-(N-carbazolyl)]phenyl-10-phenylanthracene (abbreviation: CzPA),1,4-bis[4-(N-carbazolyl)phenyl]-2,3,5,6-tetraphenylbenzene, or the likecan be used.

Further, examples of the aromatic hydrocarbons that can be used for thecomposite material include 2-tert-butyl-9,10-di(2-naphthyl)anthracene(abbreviation: t-BuDNA), 2-tert-butyl-9,10-di(1-naphthyl)anthracene,9,10-bis(3,5-diphenylphenyl)anthracene (abbreviation: DPPA),2-tert-butyl-9,10-bis(4-phenylphenyl)anthracene (abbreviation: t-BuDBA),9,10-di(2-naphthyl)anthracene (abbreviation: DNA),9,10-diphenylanthracene (abbreviation: DPAnth), 2-tert-butylanthracene(abbreviation: t-BuAnth), 9,10-bis(4-methyl-1-naphthyl)anthracene(abbreviation: DMNA),2-tert-butyl-9,10-bis[2-(1-naphthyl)phenyl]anthracene,9,10-bis[2-(1-naphthyl)phenyl]anthracene, and the like.

Furthermore, there are2,3,6,7-tetramethyl-9,10-di(1-naphthyl)anthracene,2,3,6,7-tetramethyl-9,10-di(2-naphthyl)anthracene, 9,9′-bianthryl,10,10′-diphenyl-9,9′-bianthryl,10,10′-bis(2-phenylphenyl)-9,9′-bianthryl,10,10′-bis[(2,3,4,5,6-pentaphenyl)phenyl]-9,9′-bianthryl, anthracene,tetracene, rubrene, perylene, 2,5,8,11-tetra(tert-butyl)perylene, andthe like. Besides, there are pentacene, coronene, and the like. Use ofan aromatic hydrocarbon that has a hole mobility of 1×10⁻⁶ cm²/(V.s) ormore and has 14 to 42 carbon atoms, as given above, is more preferable.

Note that the aromatic hydrocarbons that can be used for the compositematerial may have a vinyl skeleton. Examples of the aromatichydrocarbons having a vinyl skeleton include4,4′-bis(2,2-diphenylvinyl)biphenyl (abbreviation: DPVBi),9,10-bis[4-(2,2-diphenylvinyl)phenyl]anthracene (abbreviation: DPVPA),and the like. Alternatively, a high molecular compound such aspoly(N-vinylcarbazole) (abbreviation: PVK) orpoly(4-vinyltriphenylamine) (abbreviation: PVTPA) can be used.

It is preferable that a substance forming the second layer 104 be asubstance with a high hole-transport property, specifically, an aromaticamine compound (i.e., a compound having a benzene ring-nitrogen bond).As widely used materials, there are4,4′-bis[N-(3-methylphenyl)-N-phenylamino]biphenyl, derivatives thereofsuch as 4,4′-bis[N-(1-napthyl)-N-phenylamino]biphenyl (hereinafterreferred to as NPB), and star burst aromatic amine compounds such as4,4′,4″-tris(N,N-diphenyl-amino)triphenylamine, and4,4′,4″-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine.

The substances given here are mainly substances having a hole mobilityof 10⁻⁶ cm²/Vs or more. Note that any other substance may also be usedas long as it is a substance in which the hole-transport property ishigher than the electron-transport property. Further, the second layer104 is not limited to a single layer and may be a mixed layer or a stackof two or more layers including any of the above-mentioned substances.Alternatively, any of the above hole-transport materials may be added toa high molecular compound that is electrically inactive, such as PMMA.

Alternatively, any of the following high molecular compounds may beused: poly(N-vinylcarbazole) (abbreviation: PVK),poly(4-vinyltriphenylamine) (abbreviation: PVTPA),poly[N-(4-{N′-[4-(4-diphenylamino)phenyl]phenyl-N′-phenylamino}phenyl)methacrylamide](abbreviation: PTPDMA), andpoly[N,N′-bis(4-butylphenyl)-N,N′-bis(phenyl)benzidine](abbreviation:Poly-TPD). Further alternatively, to any of these high molecularcompounds, any of the above-mentioned hole-transport materials may beadded as appropriate.

The third layer 105 is a layer including a light-emitting substance(also referred to as a light-emitting layer). In Embodiment 2, the thirdlayer 105 is formed using any of the carbazole derivatives obtained by aproduction method described in Embodiment 1. The carbazole derivativesexhibit blue light emission and thus are suitable for use as alight-emitting substance in a light-emitting element. Further, thecarbazole derivatives obtained by a production method of Embodiment 1(hereinafter, simply referred to as carbazole derivatives according toan embodiment of the present invention, in some cases) can also be usedas a host of the third layer 105, and a structure in which a dopantserving as a light-emitting substance is dispersed in the carbazolederivative can provide light emission from the dopant serving as alight-emitting substance.

When any of the carbazole derivatives according to an embodiment of thepresent invention is used as a material in which another light-emittingsubstance is dispersed, an emission color depending on thelight-emitting substance can be obtained. Also, a mixture of an emissioncolor depending on the carbazole derivative according to the embodimentof the present invention and an emission color depending on thelight-emitting substance dispersed in the carbazole derivative can beobtained.

Alternatively, by formation of a light-emitting element in which any ofthe carbazole derivatives according to an embodiment of the presentinvention is included in a layer including a material (host) that has aband gap larger than the carbazole derivative, light emission from thecarbazole derivative according to the embodiment of the presentinvention can be obtained. In other words, any of the carbazolederivatives according to an embodiment of the present invention canserve as a dopant. Here, since the carbazole derivatives according to anembodiment of the invention have an extremely large band gap and emitlight of a short wavelength, a light-emitting element which can provideblue light emission with highly color purity can be formed.

Here, any of a variety of materials can be used as a light-emittingsubstance that is to be dispersed in any of the carbazole derivativesaccording to an embodiment of the present invention. Specifically, anyof the following fluorescent substances which emit fluorescence can beused:9,10-diphenyl-2-[N-phenyl-N-(9-phenyl-9H-carbazol-3-yl)amino]anthracene(abbreviation: 2PCAPA),4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran(abbreviation: DCM1),4-(dicyanomethylene)-2-methyl-6-(julolidin-4-yl-vinyl)-4H-pyran(abbreviation: DCM2), N,N-dimethylquinacridone (abbreviation: DMQd),rubrene, and the like.

Alternatively, a fluorescent substance which emits fluorescence, such asN,N′-bis[4-(9H-carbazol-9-yl)phenyl]-N,N′-diphenylstilbene-4,4′-diamine(abbreviation: YGA2S) or4-(9H-carbazol-9-yl)-4′-(10-phenyl-9-anthryl)triphenylamine(abbreviation: YGAPA), can be used. Further alternatively, aphosphorescent substances which emits phosphorescence,(acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III)(abbreviation: Ir(Fdpq)₂(acac)) or(2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrinato)platinum(II)(abbreviation: PtOEP) can be used.

For the fourth layer 106, a substance with a high electron-transportproperty can be used. For example, the fourth layer 106 is formed usinga metal complex having a quinoline or benzoquinoline skeleton, such astris(8-quinolinolato)aluminum (abbreviation: Alq),tris(4-methyl-8-quinolinolato)aluminum (abbreviation: Almq₃),bis(10-hydroxybenzo[h]quinolinato)beryllium (abbreviation: BeBq₂), orbis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum (abbreviation:BAlq), or the like. Alternatively, a metal complex having anoxazole-based or thiazole-based ligand, such asbis[2-(2-hydroxyphenyl)benzoxazolato]zinc (abbreviation: Zn(BOX)₂) orbis[2-(2-hydroxyphenyl)-benzothiazolato]zinc (abbreviation: Zn(BTZ)₂),or the like can be used.

Instead of the metal complexes, any of the following substances can beused: 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole(abbreviation: PBD),1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene(abbreviation: OXD-7),3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole(abbreviation: TAZ), bathophenanthroline (abbreviation: BPhen),bathocuproine (abbreviation: BCP), and the like. The substances givenhere are substances having an electron mobility of 10⁻⁶ cm²/(V.s) ormore. Note that any substance other than the above substances may alsobe used as long it is a substance in which the electron-transportproperty is higher than the hole-transport property. Furthermore, theelectron-transport layer is not limited to a single layer and may be astack of two or more layers each containing any of the aforementionedsubstances.

Further, a layer having a function of promoting electron injection (anelectron-inject layer) may be provided between the fourth layer 106 andthe second electrode 107. For the layer having a function of promotingelectron injection, an alkali metal, an alkaline earth metal, or acompound thereof, such as lithium fluoride (LiF), cesium fluoride (CsF),or calcium fluoride (CaF₂), can be used. For example, it is possible touse a layer including an electron-transport substance which includes analkali metal, an alkaline earth metal, or a compound thereof, a layerincluding Alq which includes magnesium (Mg), or the like. Note that theuse of a layer including an electron-transport substance which includesan alkali metal or an alkaline earth metal is more preferable, in whichcase electron injection from the second electrode 107 proceedsefficiently.

As a substance forming the second electrode 107, a metal, an alloy, anelectrically conductive compound, a mixture thereof, or the like with alow work function (specifically, a work function of 3.8 eV or lower) canbe used. As specific examples of such cathode materials, there areelements of Group 1 or Group 2 of the periodic table, i.e., alkalimetals such as lithium (Li) and cesium (Cs), alkaline earth metals suchas magnesium (Mg), calcium (Ca), and strontium (Sr), alloys containingany of these metals (e.g., MgAg and AlLi), rare earth metals such aseuropium (Eu) and ytterbium (Yb), alloys containing any of these metals,and the like.

However, for the second electrode 107, any of a variety of conductivematerials such as Al, Ag, ITO, and ITO containing silicon or siliconoxide can be used regardless of the work function by the provision ofthe layer having a function of promoting electron injection between thesecond electrode 107 and the fourth layer 106 so as to form a stack withthis second electrode.

Further, since the carbazole derivatives according to an embodiment ofthe present invention are bipolar substances which have a highelectron-transport property and a high hole-transport property, thecarbazole derivatives can also be used as a carrier-transport materialfor a functional layer of a light-emitting element. For example, any ofthe carbazole derivatives according to an embodiment of the presentinvention can be used for a hole-transport layer or anelectron-transport layer, which is a carrier-transport layer, or ahole-inject layer or an electron-inject layer.

Further, for the formation of the first layer 103, the second layer 104,the third layer 105, and the fourth layer 106, any of a variety ofmethods such as an evaporation method, a sputtering method, a dropletdischarging method (an inkjet method), a spin coating method, or aprinting method can be employed. Further, a different film formationmethod may be used for each electrode or each layer. When a wet methodis employed to form a thin film using a composition in a solution formwhich is obtained by dissolving any of the carbazole derivativesaccording to an embodiment of the present invention in a solvent, thethin film is formed in such a manner that the composition in a solutionform which includes the carbazole derivative and the solvent is attachedto a region where the thin film is to be formed, the solvent is removed,and the resulting material is solidified.

As the wet method, any of the following methods can be employed: a spincoating method, a roll coating method, a spray method, a casting method,a dipping method, a droplet discharging (ejection) method (an inkjetmethod), a dispenser method, a variety of printing methods (a method bywhich a thin film can be formed to have a desired pattern, such asscreen (stencil) printing, offset (planographic) printing, letterpressprinting, or gravure (intaglio) printing), or the like. Note that aslong as a liquid composition is used, there is no limitation on theabove-described methods and the composition of the embodiment of thepresent invention can be used.

Any of a variety of organic compounds can be used as the solvent in theabove-described composition. For example, by using a solvent that has anaromatic ring (e.g., a benzene ring), such as toluene, xylene,methoxybenzene (anisole), dodecylbenzene, or a mixed solvent ofdodecylbenzene and tetralin, any of the carbazole derivatives can bedissolved. Further, any of the above-described carbazole derivatives canalso be dissolved in a solvent that does not have an aromatic ring, suchas dimethylsulfoxide (DMSO), dimethylformamide (DMF), or chloroform.

As other examples of the solvents, there are ketone-based solvents suchas acetone, methyl ethyl ketone, diethyl ketone, n-propyl methyl ketone,and cyclohexanone, ester-based solvents such as ethyl acetate, n-propylacetate, n-butyl acetate, ethyl propionate, γ-butyrolactone, and diethylcarbonate, ether-based solvents such as diethyl ether, tetrahydrofuran,and dioxane, alcohol-based solvents such as ethanol, isopropanol,2-methoxyethanol, and 2-ethoxyethanol, and the like.

The composition described in Embodiment 2 may further include anotherorganic material. As the organic material, there are aromatic compoundsor heteroaromatic compounds which are solid at room temperature. A lowmolecular compound or a high molecular compound can be used as theorganic material. When a low molecular compound is used, a low molecularcompound having a substituent that improves the solubility in a solventis preferably used. The composition may further include a binder inorder to improve film properties of a film that is to be formed. As thebinder, a high molecular compound that is electrically inactive ispreferably used. Specifically, polymethylmethacrylate (abbreviation:PMMA), polyimide, or the like can be used.

In the light-emitting element of Embodiment 2 which has the structure asdescribed above, the potential difference generated between the firstelectrode 102 and the second electrode 107 makes a current flow, wherebyholes and electrons recombine in the third layer 105 which is a layerincluding a high light-emitting property and accordingly light isemitted. In other words, a light-emitting region is formed in the thirdlayer 105. The emitted light is extracted out through one or both of thefirst electrode 102 and the second electrode 107. Therefore, one or bothof the first electrode 102 and the second electrode 107 is/are anelectrode having a light-transmitting property.

When only the first electrode 102 is a light-transmitting electrode,light is extracted from the substrate side through the first electrode102, as illustrated in FIG. 1A. In contrast, when only the secondelectrode 107 is a light-transmitting electrode, light is extracted froma side opposite to the substrate side through the second electrode 107,as illustrated in FIG. 1B. When both the first electrode 102 and thesecond electrode 107 are light-transmitting electrodes, light isextracted from both the substrate side and the side opposite to thesubstrate side through the first electrode 102 and the second electrode107, as illustrated in FIG. 1C.

Note that the structure of the layers provided between the firstelectrode 102 and the second electrode 107 is not limited to the abovestructure and may be any structure as long as the light-emitting regionfor recombination of holes and electrons is positioned away from thefirst electrode 102 and the second electrode 107 so as to suppressquenching by the light-emitting region being close to metal. In otherwords, there is no particular limitation on the stack structure of thelayers as long as the light-emitting layer including any of thecarbazole derivatives according to an embodiment of the presentinvention is freely combined with the layer including a substance with ahigh electron-transport property, the layer including a substance with ahigh hole-transport property, the layer including a substance with ahigh electron-inject property, the layer including a substance with ahigh hole-inject property, the layer including a bipolar substance (asubstance with a high electron-transport and a high hole-transportproperty), the layer including a hole-blocking material, etc.

In a light-emitting element illustrated in FIG. 2, an EL layer 308 isprovided between a first electrode 302 and a second electrode 307 over asubstrate 301. The EL layer 308 has a first layer 303 including asubstance with a high electron-transport property, a second layer 304including a light-emitting substance, a third layer 305 including asubstance with a high hole-transport property, and a fourth layer 306including a substance with high hole-inject property. The firstelectrode 302 which is to function as a cathode, the first layer 303including a substance with a high electron-transport property, thesecond layer 304 including a light-emitting substance, the third layer305 including a substance with a high hole-transport property, thefourth layer 306 including a substance with high hole-inject property,and the second electrode 307 which is to function as an anode arestacked in that order.

Hereinafter, a method of forming the light-emitting element will bedescribed in specific terms. The light-emitting element of Embodiment 2has a structure in which an EL layer is interposed between a pair ofelectrodes. The EL layer includes at least the layer including alight-emitting substance (also referred to as a light-emitting layer)which is formed using any of the carbazole derivatives according to anembodiment of the present invention. The EL layer may include thefunctional layer (the hole-inject layer, the hole-transport layer, theelectron-transport layer, the electron-inject layer, etc.). Theelectrodes (the first electrode and the second electrode), the layerincluding a light-emitting substance, and the functional layer may beformed by any of the wet methods such as a droplet discharging method(an inkjet method), a spin coating method, or a printing method, or by adry method such as a vacuum evaporation method, a CVD method, or asputtering method.

The use of a wet method enables the formation at atmospheric pressure,which can be achieved with a simple device and process, and thus has theeffects of simplifying the process and improving the productivity. Incontrast, in a dry method, dissolution of a material is not needed, andthus a material that has low solubility in a solution can be used toexpand the range of material choices. All the thin films included in thelight-emitting element may be formed by a wet method. In this case, thelight-emitting element can be formed with only facilities needed for awet method.

Alternatively, the stack up to the layer including a light-emittingsubstance may be formed by a wet method, and the functional layer, thesecond electrode, etc. which are stacked on the layer including alight-emitting substance may be formed by a dry method. Furtheralternatively, the first electrode and the functional layer may beformed by a dry method before the formation of the layer including alight-emitting substance, and the layer including a light-emittingsubstance, the functional layer stacked thereover, and the secondelectrode may be formed by a wet method. Needless to say, the embodimentof the present invention is not limited to this example, and thelight-emitting element can be formed by appropriate selection from a wetmethod and a dry method depending on a material that is to be used,necessary film thickness, and the interface state.

In Embodiment 2, the light-emitting element is formed over a substratemade of glass, plastic, or the like. By formation of a plurality of suchlight-emitting elements over one substrate, a passive matrixlight-emitting device can be fabricated. Alternatively, thelight-emitting element may be formed over an electrode that iselectrically connected to, for example, a TFT (thin film transistor)formed over a substrate formed using glass, plastic, or the like. Thus,an active matrix light-emitting device in which driving of thelight-emitting element is controlled by a TFT can be fabricated.

Note that there is no limitation on the structure of a TFT, and astaggered TFT or an inverted staggered TFT may be used. In addition,there is no limitation on crystallinity of a semiconductor used for theTFT, and an amorphous semiconductor may be used, or a crystallinesemiconductor may be used. Further, a driving circuit formed over a TFTsubstrate may be formed using an n-channel TFT and a p-channel TFT, ormay be formed using any one of an n-channel TFT or a p-channel TFT.

The carbazole derivatives according to an embodiment of the presentinvention have an extremely large band gap. Therefore, even with the useof a dopant that emits light of a relatively short wavelength,particularly blue light, light emission not from the carbazolederivative but from the dopant can be efficiently obtained. Further,these carbazole derivatives have a wide band gap and are bipolarsubstances which have a high electron-transport property and a highhole-transport property. Accordingly, by using any of the carbazolederivatives according to the embodiment of the present invention for alight-emitting element, the highly reliable light-emitting element witha good carrier balance can be obtained. Furthermore, with the use of anyof these derivatives, a highly reliable light-emitting device andelectronic device can be obtained.

Embodiment 3

In Embodiment 3, light-emitting elements having structures that aredifferent from those of the light-emitting elements given in Embodiment2 will be described using FIGS. 3A and 3B. In Embodiment 3, asillustrated in FIG. 3A, a layer 130 for controlling transport ofelectron carriers are provided between the fourth layer 106 which is anelectron-transport layer and the third layer 105 which is alight-emitting layer (also referred to as a light-emitting layer 105).Thus, a layer for controlling transport of electron carriers may beprovided between an electron-transport layer and a light-emitting layer.

This layer for controlling transport of electron carriers is formed byadding a small amount of substance with a high electron-trappingproperty to a material with a high electron-transport property asaforementioned, or alternatively, by adding a material with a low LUMO(lowest unoccupied molecular orbital) energy level and a hole-transportproperty to a material with a high electron-transport property. Bysuppressing transport of electron carriers, the carrier balance can beadjusted. Such a structure is very effective in suppressing problems(e.g., shortening of element lifetime) caused when electrons passthrough the third layer 105.

As another structure, the light-emitting layer 105 may include aplurality of layers which are two or more layers. FIG. 3B illustrates anexample in which the light-emitting layer 105 includes a plurality oflayers which are two layers: a first light-emitting layer 105 a and asecond light-emitting layer 105 b. For example, when the firstlight-emitting layer 105 a and the second light-emitting layer 105 b arestacked in that order from the second layer 104 side which is ahole-transport layer to form the light-emitting layer 105, a structurein which a substance with a hole-transport property is used as the hostmaterial of the first light-emitting layer 105 a and a substance with anelectron-transport property is used for the second light-emitting layer105 b may be employed.

For a light-emitting layer, any of the carbazole derivatives accordingto an embodiment of the present invention can be used alone or as a hostor even as a dopant. When any of these carbazole derivatives is used asa host, a structure in which a dopant is dispersed in the carbazolederivative according to the embodiment of the present invention canprovide light emission from the dopant. Alternatively, when any of thecarbazole derivatives according to the embodiment of the presentinvention is used as a dopant, a structure in which the carbazolederivative is included in a layer containing a material (host) that hasa band gap larger than the derivative can provide light emission fromthe carbazole derivative according to the embodiment of the presentinvention.

Further, the carbazole derivatives according to an embodiment of thepresent invention are bipolar substances which have a hole-transportproperty and a high electron-transport property. Therefore, for use ofthe hole-transport property, any of the carbazole derivatives can beused for the first light-emitting layer 105 a, or for use of theelectron-transport property, any of the carbazole derivatives can beused for the first light-emitting layer 105 b. For each of thelight-emitting layers 105 a and 105 b, the carbazole derivative can beused alone or as a host material or even as a dopant material. When anyof the carbazole derivatives is used alone or as a host material, whichof the light-emitting layer 105 a with a hole-transport property and thelight-emitting layer 105 b with an electron-transport property includesthe derivative may depend on the carrier-transport property of thecarbazole derivative. Note that Embodiment 3 can be combined with anyother embodiment as appropriate.

Embodiment 4

In Embodiment 4, an example of a light-emitting element including astack of a plurality of units (also referred to as a stacked-typeelement) in which one unit means any of the light-emitting elementsdescribed in Embodiment 2 will be described with reference to FIG. 4. Inthis light-emitting element, a plurality of light-emitting units areformed between a first electrode and a second electrode. Note that information of such a light-emitting element including a stack of aplurality of units, electrodes that would be located between the unitsare omitted.

In FIG. 4, a first light-emitting unit 511 and a second light-emittingunit 512 are stacked between a first electrode 501 and a secondelectrode 502. Electrodes that are similar to the electrodes ofEmbodiment 2 can be applied to the first electrode 501 and the secondelectrode 502. Further, the first light-emitting unit 511 and the secondlight-emitting unit 512 may have either the same or different structure,which can be similar to those described in Embodiment 2.

A charge generation layer 513 includes a composite material of anorganic compound and a metal oxide. This composite material of anorganic compound and a metal oxide corresponds to the composite materialdescribed in Embodiment 2 and includes an organic compound and a metaloxide such as V₂O₅, MoO₃, or WO₃. As the organic compound, any ofvariety of compounds such as aromatic amine compounds, carbazolederivatives, aromatic hydrocarbons, oligomers, dendrimers, or highmolecular compounds (such as polymers) can be used.

Further, as the organic compound, an organic compound having a holemobility of 10⁻⁶ cm²/(V.s) or more is preferably applied. Note that asubstance other than these compounds may also be used as long as it is asubstance in which the hole-transport property is higher than theelectron-transport property. Since the composite material of an organiccompound and a metal oxide has an excellent carrier-inject property andcarrier-transport property, low-voltage driving or low-current drivingcan be realized.

Alternatively, for the charge generation layer 513, the compositematerial of an organic compound and a metal oxide may be combined withanother material. For example, a layer including the composite materialof an organic compound and a metal oxide may be combined with a layerincluding one compound selected from among electron-donating substancesand a compound having a high electron-transport property. Furtheralternatively, for the charge generation layer 513, a layer includingthe composite material of an organic compound and a metal oxide may becombined with a transparent conductive film.

In any case, the charge generation layer 513 interposed between thefirst light-emitting unit 511 and the second light-emitting unit 512 mayhave any structure as long as electrons can be injected into thelight-emitting unit on one side and holes can be injected into thelight-emitting unit on the other side when a voltage is applied betweenthe first electrode 501 and the second electrode 502.

In Embodiment 4, the light-emitting element having two light-emittingunits is described. However, the present invention can be applied to alight-emitting element in which three or more light-emitting units arestacked. As in the light-emitting element according to Embodiment 4, byarranging a plurality of light-emitting units between a pair ofelectrodes so that the plurality of light-emitting units can bepartitioned by a charge generation layer, light emission in a highluminance region can be achieved with current density kept low; thus, alight-emitting element having long lifetime can be realized. Further,when the light-emitting element is applied to a lighting apparatus,voltage drop due to the resistance of the electrode materials can besuppressed; accordingly, uniform light emission in a large area can beachieved. Furthermore, a light-emitting device capable of low-voltagedriving with low power consumption can be realized. Note that Embodiment4 can be combined with any other embodiment as appropriate.

Embodiment 5

In Embodiment 5, a light-emitting device formed using any of thecarbazole derivatives according to an embodiment of the presentinvention is described using FIGS. 5A and 5B. FIG. 5A is a top viewillustrating the light-emitting device, and FIG. 5B is a cross-sectionalview of FIG. 5A which is taken along lines A-B and C-D. Referencenumeral 601 denotes a driver circuit portion (a source side drivercircuit), reference numeral 602 denotes a pixel portion, and referencenumeral 603 denotes a driver circuit portion (a gate side drivercircuit), which are shown by a dotted line. Further, reference numeral604 denotes a sealing substrate, and reference numeral 605 denotes asealing material. Reference numeral 607 denotes a space surrounded bythe sealing material 605

Note that a leading wiring 608 is a wiring for transmitting signals thatare input to the source side driver circuit 601 and the gate side drivercircuit 603. The leading wiring 608 receives video signals, clocksignals, start signals, reset signals, and the like from an FPC(flexible printed circuit) 609 serving as an external input terminal.Note that although only an FPC is illustrated here, this FPC may beprovided with a PWB (printed wiring board). The light-emitting device inthis specification includes not only a light-emitting device itself butalso a light-emitting device to which an FPC or a PWB is attached.

Then, a cross-sectional structure will be described using FIG. 5B. Thedriver circuit portions and the pixel portion are provided over anelement substrate 610, but only the source side driver circuit 601 whichis the driver circuit portion and one pixel of the pixel portion 602 areillustrated. In the source side driver circuit 601, a CMOS circuit whichis a combination of an n-channel TFT 623 and a p-channel TFT 624 isformed. The driver circuits may be formed using any of various types ofcircuits such as a CMOS circuit, a PMOS circuit, and an NMOS circuit.Note that in Embodiment 5, a driver-integrated type in which a drivercircuit is formed over a substrate provided with a pixel portion isdescribed; however, the present invention is not limited to this type,and the driver circuit can be formed outside the substrate instead ofbeing formed over the substrate provided with the pixel portion.

Further, the pixel portion 602 includes a plurality of pixels eachhaving a switching TFT 611, a current controlling TFT 612, and a firstelectrode 613 which is electrically connected to a drain of the currentcontrolling TFT 612. Note that an insulator 614 is formed to cover anend portion of the first electrode 613. Here, a positive photosensitiveacrylic resin film is used to form the insulator 614.

Furthermore, in order to improve coverage, the insulator 614 is providedsuch that either an upper end portion or a lower end portion of theinsulator 614 has a curved surface with a curvature. For example, when apositive photosensitive acrylic resin is used as a material for theinsulator 614, it is preferable that only the upper end portion of theinsulator 614 have a curved surface with a radius of curvature (0.2 to 3μm). Alternatively, the insulator 614 can be formed using either anegative type that becomes insoluble in an etchant by light irradiationor a positive type that becomes soluble in an etchant by lightirradiation.

A layer 616 including a light-emitting substance and a second electrode617 are formed over the first electrode 613. Here, it is preferable thatthe first electrode 613 serving as an anode be formed using a materialwith a high work function. For example, the first electrode 613 can beformed using a single-layer film of an ITO film, a film of indium tinoxide containing silicon, a film of indium oxide containing zinc oxideat 2 to 20 wt %, a titanium nitride film, a chromium film, a tungstenfilm, a Zn film, a Pt film, or the like, a stack of a titanium nitridefilm and a film containing aluminum as the main component, a stack ofthree layers: a titanium nitride film, a film containing aluminum as themain component, and another titanium nitride film, or the like. Notethat with the use of a stack structure, resistance as a wiring is low, agood ohmic contact is formed, and further, the first electrode 613 canbe made to function as an anode.

In addition, the layer 616 including a light-emitting substance isformed by any of a variety of methods, for example, an evaporationmethod using an evaporation mask, a droplet discharging method such asan inkjet method, a printing method, or a spin coating method. The layer616 including a light-emitting substance includes any of the carbazolederivatives described in Embodiment 1. Further, another materialincluded in the layer 616 including a light-emitting substance may be alow molecular material, an oligomer, a dendrimer, or a high molecularmaterial.

As a material used for the second electrode 617 which is formed over thelayer 616 including a light-emitting substance and functions as acathode, a material having a low work function (e.g., Al, Mg, Li, Ca, analloy or a compound thereof such as MgAg, MgIn, AlLi, LiF, or CaF₂) ispreferably used. Note that when light generated in the layer 616including a light-emitting substance is transmitted through the secondelectrode 617, the second electrode 617 may be a stack of a metal thinfilm with a reduced thickness and a transparent conductive film (e.g., afilm of ITO, indium oxide containing zinc oxide at 2 to 20 wt %, indiumoxide-tin oxide containing silicon or silicon oxide, or ZnO (zincoxide)).

Furthermore, by attaching the sealing substrate 604 and the elementsubstrate 610 to each other with the sealing material 605, alight-emitting element 618 is provided in the space 607 surrounded bythe element substrate 610, the sealing substrate 604, and the sealingmaterial 605. Note that the space 607 is filled with a filler, and hereare also cases where the space 607 may be filled with an inert gas(e.g., nitrogen or argon) as such a filler, or where the space 607 maybe filled with the sealing material 605. As the sealing material 605, anepoxy-based resin is preferably used. In addition, it is preferable thatsuch a material allow penetration of as little moisture or oxygen aspossible.

Furthermore, as a material used for the sealing substrate 604, a plasticsubstrate made of FRP (fiberglass-reinforced plastics), PVF (polyvinylfluoride), polyester, acrylic, or the like can be used in addition to aglass substrate or a quartz substrate. As described above, alight-emitting device fabricated using any of the carbazole derivativesaccording to an embodiment of the present invention can be obtained.

The carbazole derivatives have a wide band gap and are bipolarsubstances which have a high electron-transport property and a highhole-transport property. Accordingly, by using any of the carbazolederivatives according to the embodiment of the present invention for alight-emitting element, the highly reliable light-emitting element witha good carrier balance can be obtained. Furthermore, with the use of anyof the carbazole derivatives according to the embodiment of the presentinvention, a highly reliable light-emitting device and electronic devicecan be obtained.

Although an active matrix light-emitting device which controls drivingof a light-emitting element with a transistor is thus described inEmbodiment 5, the light-emitting device may be a passive matrixlight-emitting device. FIGS. 6A and 6B illustrate a passive matrixlight-emitting device fabricated using any of the carbazole derivativesaccording to an embodiment of the present invention. In FIGS. 6A and 6B,a layer 955 including a light-emitting substance is provided between anelectrode 952 and an electrode 956 over a substrate 951. An end portionof the electrode 952 is covered with an insulating layer 953. Inaddition, a partition layer 954 is provided over the insulating layer953.

The sidewalls of the partition layer 954 slope so that the distancebetween one sidewall and the other sidewall gradually decreases towardthe surface of the substrate. In other words, a cross section takenalong the direction of the short side of the partition layer 954 istrapezoidal, and the lower side (a side in contact with the insulatinglayer 953, which is one of a pair of parallel sides of the trapezoidalcross section) is shorter than the upper side (a side not in contactwith the insulating layer 953, which is the other of the pair ofparallel sides). By the provision of the partition wall layer 954 inthis manner, defects of the light-emitting element due to static chargeor the like can be prevented. Also in the case of a passive matrixlight-emitting device, by including a light-emitting element accordingto an embodiment of the present invention, a highly reliablelight-emitting device can be obtained.

Embodiment 6

In Embodiment 6, electronic devices each including a light-emittingdevice described in Embodiment 5 will be described. The electronicdevices of Embodiment 6 each have a highly reliable display portionincluding any of the carbazole derivatives described in Embodiment 1.

Examples of these electronic devices having a light-emitting elementformed using any of the carbazole derivatives include cameras such asvideo cameras and digital cameras, goggle type displays, navigationsystems, audio replay devices (e.g., car audio systems and audiosystems), computers, game machines, portable information terminals(e.g., mobile computers, cellular phones, portable game machines, andelectronic book readers), image replay devices in which a recordingmedium is provided (specifically, devices that are capable of replayingrecording media such as DVDs (digital versatile discs) and equipped witha display device that can display an image), and the like. Specificexamples of such electronic devices are illustrated in FIGS. 7A to 7D.

FIG. 7A illustrates a display device according to Embodiment 6, whichincludes a housing 8001, a supporting base 8002, a display portion 8003,a speaker portion 8004, video input terminals 8005, and the like. Notethat the category of the display device includes all types ofinformation display devices, for example, display devices for a personalcomputer, display devices for TV broadcast reception, display devicesfor advertisement display, and the like. In this display device, thedisplay portion 8003 has light-emitting elements similar to thosedescribed in Embodiment 2 or Embodiment 3, which are arranged in matrix.

A feature of each light-emitting element is high reliability. Thedisplay portion 8003 including the light-emitting elements has a similarfeature. Accordingly, in this display device, the amount of imagedisplay deterioration is small, and reliability is improved. With such afeature, a circuit having a function of compensating for deteriorationor power supply circuits in the display device can be significantlyreduced or downsized; accordingly, a reduction in the size and weight ofthe housing 8001 or the supporting base 8002 can be achieved.

FIG. 7B illustrates a computer according to Embodiment 6, which includesa housing 8102, a display portion 8103, a keyboard 8104, an externalconnection port 8105, a pointing device 8106, and the like. In thiscomputer, the display portion 8103 includes light-emitting elementssimilar to those described in Embodiment 2 or Embodiment 3, which arearranged in matrix. A feature of each light-emitting element is highreliability. The display portion 8103 including the light-emittingelements has a similar feature. Accordingly, in this computer, theamount of image display deterioration is small, and reliability isimproved. With such a feature, a circuit having a function ofcompensating for deterioration or power supply circuits in the computercan be significantly reduced or downsized; accordingly, a reduction inthe size and weight of the computer can be achieved.

FIG. 7C illustrates a video camera according to Embodiment 6, whichincludes a display portion 8202, an external connection port 8204, aremote control receiving portion 8205, an image receiving portion 8206,operation keys 8209, and the like. In this video camera, the displayportion 8202 includes light-emitting elements similar to those describedin Embodiment 2 or Embodiment 3, which are arranged in matrix. A featureof each light-emitting element is high reliability. The display portion8202 including the light-emitting elements has a similar feature.Accordingly, in this video camera, the amount of image displaydeterioration is small, and reliability is improved. With such afeature, a circuit having a function of compensating for deteriorationor power supply circuits in the video camera can be significantlyreduced or downsized; accordingly, a reduction in size and weight can beachieved. Thus, a product that is suitable for being carried around canbe provided.

FIG. 7D illustrates a cellular phone according to Embodiment 6, whichincludes a display portion 8403, an audio input portion 8404, an audiooutput portion 8405, operation keys 8406, an external connection port8407, and the like. In this cellular phone, the display portion 8403includes light-emitting elements similar to those described inEmbodiment 2 or Embodiment 3, which are arranged in matrix. A feature ofeach light-emitting element is high reliability. The display portion8403 including the light-emitting elements has a similar feature.Accordingly, in this cellular phone, the amount of image displaydeterioration is small, and reliability is improved. With such afeature, a circuit having a function of compensating for deteriorationor power supply circuits in the cellular phone can be significantlyreduced or downsized; accordingly, a reduction in the size and weight ofthe main body can be achieved. In the cellular phone according toEmbodiment 6, high image quality and a reduction in size and weight areachieved. Accordingly, a product that is suitable for being carriedaround can be provided.

As described above, the applicable range of a light-emitting deviceaccording to an embodiment of the present invention is wide so that thislight-emitting device can be applied to electronic devices in a varietyof fields. With the use of any of the carbazole derivatives according toan present invention, an electronic device including a highly reliabledisplay portion can be provided. Further, the light-emitting deviceaccording to the embodiment of the present invention can also be used asa lighting device. An example in which a light-emitting elementaccording to an embodiment of the present invention is used for alighting device will be described using FIG. 8.

FIG. 8 illustrates an example of a liquid crystal display device inwhich a light-emitting device according to an embodiment of the presentinvention is used as a backlight. The liquid crystal display deviceillustrated in FIG. 8 includes a housing 901, a liquid crystal layer902, a backlight 903, and a housing 904, and the liquid crystal layer902 is connected to a driver IC 905. In addition, the light-emittingdevice according to the embodiment of the present invention is used asthe backlight 903, and a current is supplied by a terminal 906.

By using a light-emitting device according to an embodiment of thepresent invention as a backlight of a liquid crystal display device, thehighly reliable backlight can be obtained. Further, the light-emittingdevice according to the embodiment of the invention is a lighting devicewith plane light emission, and can have a large area. Therefore, thebacklight can have a large area, and a liquid crystal display devicehaving a large area can be obtained. Furthermore, since thelight-emitting device according to the embodiment of the presentinvention is thin, the display device can also be thin.

FIG. 9 illustrates an example in which a light-emitting device accordingto an embodiment of the present invention is used as a desk lamp, whichis one of lighting apparatus. The desk lamp illustrated in FIG. 9includes a housing 2001 and a light source 2002, and the light-emittingdevice according to the embodiment of the present invention is used asthe light source 2002. Since the light-emitting device according to theembodiment of the present invention is highly reliable, the desk lamp isalso highly reliable. FIG. 10 illustrates an example in which alight-emitting device according to an embodiment of the presentinvention is used as an interior lighting apparatus 3001. Since thelight-emitting device according to the embodiment of the presentinvention can have a large area, the light-emitting device can be usedas a lighting apparatus having a large area. Furthermore, since thelight-emitting device according to the embodiment of the presentinvention is thin, the light-emitting device can be used as a lightingapparatus that is thin.

Examples of Production of Carbazole Derivatives

Hereinafter, Examples 1 to 7 will be described as seven examples ofmethods for producing carbazole derivatives according to an embodimentof the present invention. However, it is natural that the presentinvention is not limited to these examples and is specified in the scopeof claims.

Example 1 Example of Production of CzPAP

In Example 1, an example in which3-phenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation:CzPAP) represented by the above Structural Formula 1 is produced will bedescribed. The synthesis reaction of this example includes two steps:Step 1 and Step 2.

[Step 1]

This step is a step of synthesizing3-bromo-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole. Step 1 isillustrated in Reaction Formula (E1-1) and will be detailed hereinbelow.

In a 1 L Erlenmeyer flask were added 5.0 g (10 mmol) of9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: CzPA), 600mL of ethyl acetate, and 150 mL of toluene. This mixture was heated toabout 50° C. or more and stirred to confirm dissolution of CzPA. To thissolution was added 1.8 g (10 mmol) of N-bromosuccinimide (NBS). Thissolution was stirred at room temperature for 5 days under air.

After the solution was stirred, about 150 mL of an aqueous sodiumthiosulfate solution was added to this solution, and the resultingsolution was stirred for 1 hour. The organic layer of this mixture waswashed with water, and the aqueous layer was extracted with toluene. Theextract and the organic layer were combined and washed with saturatedbrine. The organic layer was dried with magnesium sulfate, and thismixture was gravity filtered. The resulting filtrate was concentrated togive a light yellow solid. The solid obtained was recrystallized with amixed solvent of toluene and hexane to give the desired substance as 5.2g of a light yellow powder in a yield of 90%.

[Step 2]

This step is a step of synthesizing3-phenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation:CzPAP). The step is illustrated in Reaction Formula (E1-2) and will bedetailed hereinbelow.

In a 300 mL three neck flask were put 3.5 g (6.1 mmol) of3-bromo-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole, 0.74 g (6.1mmol) of phenylboronic acid, and 0.36 g (1.2 mmol) oftri(ortho-tolyl)phosphine. The atmosphere in the flask was replaced withnitrogen. To this mixture were added 60 mL of toluene, 20 mL of ethanol,and 5.0 mL of an aqueous potassium carbonate solution (2.0 mol/L). Thismixture was stirred to be degassed while the pressure was reduced. Tothis mixture was added 55 mg (0.24 mmol) of palladium(II) acetate. Thismixture was stirred under a nitrogen stream at 80° C. for 2 hours.

After this mixture was stirred, the aqueous layer of this mixture wasextracted with toluene. The extract and the organic layer were combinedand washed with saturated brine. The organic layer was dried withmagnesium sulfate, and this mixture was gravity filtered. An oilysubstance obtained by concentration of the resulting filtrate wasdissolved in about 10 mL of toluene. This solution was suction filteredthrough Celite (manufactured by Wako Pure Chemical Industries, Ltd.,Catalog No. 531-16855), alumina, and Florisil (manufactured by Wako PureChemical Industries, Ltd., Catalog No. 540-00135). An oily substanceobtained by concentration of the resulting filtrate was purified bysilica gel column chromatography (the developing solvent was a mixedsolvent of a 5:1 ratio of hexane to toluene) to give a light yellowsolid.

This light yellow solid was recrystallized with a mixed solvent oftoluene and hexane to give the desired substance as 1.3 g of a lightyellow powder in a yield of 37%. Sublimation purification of 1.3 g ofthe light yellow powder obtained was performed by a train sublimationmethod. The light yellow powder was heated at 270° C. with an argon flowrate of 4.0 mL/min under reduced pressure. After the sublimationpurification, 1.2 g of a light yellow solid which was the desiredcompound was obtained in a yield of 89%.

By a nuclear magnetic resonance (NMR) method, this compound wasconfirmed to be 3-phenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole(abbreviation: CzPAP) which was the desired compound. The following aredata of the ¹H NMR measurement of the compound obtained: ¹H NMR (CDCl₃,300 MHz): δ=7.35-7.66 (m, 14H), 7.69-7.78 (m, 9H), 7.86 (d, J=8.1 Hz,4H), 8.25 (d, J=7.8 Hz, 1H), 8.42 (s, 1H)

In addition, FIGS. 11A and 11B show ¹H NMR charts. Note that FIG. 11B isa chart showing an enlarged part in the range of 7.1 ppm to 8.5 ppm inFIG. 11A.

Further, thermogravimetry-differential thermal analysis (TG-DTA) ofCzPAP which was obtained was carried out. A high vacuum differentialtype differential thermal balance (TG-DTA2410SA, manufactured by BrukerAXS K.K.) was used. Accordingly, the temperature at which the weight wasreduced to 95% of the weight at the start of the measurement (5% weightloss temperature) at atmospheric pressure was 404° C. This demonstratesthat CzPAP has significantly high heat resistance.

FIG. 12 shows an absorption spectrum of a toluene solution of CzPAP, andFIG. 13 shows an absorption spectrum of a thin film of CzPAP. Anultraviolet-visible spectrophotometer (V-550, manufactured by JASCOCorporation) was used for the measurement. The solution was put to aquartz cell to prepare a sample, and the thin film was obtained byevaporation to a quartz substrate to prepare a sample. FIG. 12 and FIG.13 show the absorption spectrum of the toluene solution which wasobtained by subtracting the absorption spectrum of a quartz cell thatincludes only toluene and the absorption spectrum of the thin film whichwas obtained by subtracting the absorption spectrum of the quartzsubstrate, respectively. In FIG. 12 and FIG. 13, the horizontal axisrepresents wavelength (nm) and the vertical axis represents absorptionintensity (arbitrary unit). In the case of the toluene solution,absorption was observed at around 340 nm, 357 nm, 376 nm, and 397 nm. Inthe case of the thin film, absorption was observed at around 268 nm, 303nm, 341 nm, 361 nm, 382 nm, and 403 nm.

Further, FIG. 14 shows an emission spectrum of the toluene solution ofCzPAP (an excitation wavelength of 372 nm). FIG. 15 shows an emissionspectrum of the thin film of CzPAP (an excitation wavelength of 399 nm).In FIGS. 14 and 15, the horizontal axis represents wavelength (nm) andthe vertical axis represents emission intensity (arbitrary unit). In thecase of the toluene solution, the maximum emission wavelength was 423 nm(an excitation wavelength of 372 nm). In the case of the thin film, themaximum emission wavelength was 444 nm (an excitation wavelength of 399nm).

In addition, by measurement of a thin film of CzPAP in an atmosphereusing a photoelectron spectrometer (AC-2, manufactured by Riken KeikiCo., Ltd.), the HOMO level was −5.84 eV. Furthermore, with the use ofthe absorption spectrum data of the thin film of CzPAP in FIG. 13, theabsorption edge was obtained by a Tauc plot assuming direct transition.The absorption edge was estimated as an optical energy gap, whereby theenergy gap was 2.94 eV. The LUMO level estimated from the HOMO level andthe energy gap of CzPAP was −2.90 eV.

Further, the oxidation-reduction characteristics of CzPAP were measuredby cyclic voltammetry (CV). Note that an electrochemical analyzer (ALSmodel 600A, a product of BAS Inc.) was used. For a solution used in theCV measurement, dehydrated dimethylformamide (DMF, produced bySigma-Aldrich Inc., 99.8%, Catalog No. 22705-6) was used as a solvent.

At that time, tetra-n-butylammonium perchlorate (n-Bu₄NClO₄, produced byTokyo Chemical Industry Co., Ltd., Catalog No. T0836), which was asupporting electrolyte, was dissolved in the solvent such that theconcentration of tetra-n-butylammonium perchlorate was 100 mmol/L.Furthermore, the substance that is to be measured was dissolved in thesolution such that the concentration thereof was 1 mmol/L. In addition,a platinum electrode (PTE platinum electrode, produced by BAS Inc.) wasused as a working electrode, a platinum electrode (Pt counter electrodefor VC-3, (5 cm), produced by BAS Inc.) was used as an auxiliaryelectrode, and an Ag/Ag⁺ electrode (RE5 reference electrode fornonaqueous solvent, produced by BAS Inc.,) was used as a referenceelectrode. Note that the measurement was conducted at room temperature.

The oxidation characteristics of CzPAP were examined by 100 cycles ofmeasurements in which a scan for changing the potential of the workingelectrode with respect to the reference electrode from −0.01V to 1.15 Vand then from 1.15 V to −0.01 V was set to one cycle. Note that the scanrate for the CV measurements was set to 0.1 V/s. Further, the reductioncharacteristics of CzPAP were examined by 100 cycles of measurements inwhich a scan for changing the potential of the working electrode withrespect to the reference electrode from −1.45 V to −2.35 V and then from−2.35 V to −1.45 V was set to one cycle. Note that the scan rate for theCV measurements was set to 0.1V/s.

FIG. 16 shows CV measurement results of the oxidation characteristics ofCzPAP, and FIG. 17 shows CV measurement results of the reductioncharacteristics of CzPAP. In FIGS. 16 and 17, the horizontal axisrepresents potential (V) of the working electrode with respect to thereference electrode, and the vertical axis represents value of a current(PA) flowing between the working electrode and the auxiliary electrode.From FIG. 16, a current exhibiting oxidation is observed at around +0.84V (vs. the Ag/Ag⁺ electrode). From FIG. 17, a current exhibitingreduction is observed at around −2.21V (vs. the Ag/Ag⁺ electrode).

After the 100 cycles of measurements in which the scan was repeated,there was no significant change in the peak position and peak intensityof the CV curves exhibiting the oxidation and reduction reactions. Thepeak intensity for the oxidation characteristics maintained 82% of theinitial state, and the peak intensity for the reduction characteristicsmaintained 94% of the initial state. Accordingly, it is found that thecarbazole derivative according to Example 1 is stable to repetitiveoxidation-reduction reactions.

Examples in which CzPAP produced in Example 1 is produced by each of thefirst and second known production methods described above will bedescribed below. These examples are described for comparison andreference. Comparative Example 1 corresponds to the first known method,and Comparative Example 2 corresponds to the second known method.

Comparative Example 1 Synthesis of CzPAP by First Known Method

In Comparative Example 1, an example will be described in which3-phenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation:CzPAP) represented by Structural Formula 1 is produced by the firstknown method which is a known production method, as described above.

[Step 1]

This step is a step of synthesizing 3-phenyl-9H-carbazole. The step isillustrated in Reaction Formula (R1-1) and will be detailed hereinbelow.

In a 100 mL three neck flask were put 0.50 g (2.0 mmol) of3-bromo-9H-carbazole, 0.25 g (2.0 mmol) of phenylboronic acid, and 0.15g (0.50 mmol) of tri(ortho-tolyl)phosphine. The atmosphere in the flaskwas replaced with nitrogen. To this mixture were added 30 mL of toluene,10 mL of ethanol, and 2.0 mL of an aqueous potassium carbonate solution(2.0 mol/L). This mixture was stirred to be degassed while the pressurewas reduced. To this mixture was added 23 mg (0.10 mmol) ofpalladium(II) acetate. This mixture was stirred under a nitrogen streamat 80° C. for 2 hours.

After this mixture was stirred, the aqueous layer was extracted withtoluene. The extract and the organic layer were combined and washed withsaturated brine. Then, the mixture was separated into an aqueous layerand an organic layer. The organic layer was dried with magnesiumsulfate, and this mixture was gravity filtered. A solid obtained byconcentration of the resulting filtrate was dissolved in about 10 mL oftoluene. This solution was suction filtered through Celite (manufacturedby Wako Pure Chemical Industries, Ltd., Catalog No. 531-16855), alumina,and Florisil (manufactured by Wako Pure Chemical Industries, Ltd.,Catalog No. 540-00135). The resulting filtrate was concentrated to givea white solid. This solid was recrystallized with a mixed solvent oftoluene and hexane to give the desired substance as 0.23 g of a whitepowder in a yield of 47%.

[Step 2]

This step is a step of synthesizing3-phenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation:CzPAP). The step is illustrated in Reaction Formula (R1-2) and will bedetailed hereinbelow.

In a 100 mL three neck flask were put 0.39 g (0.94 mmol) of9-(4-bromophenyl)-10-phenylanthracene, 0.23 g (0.94 mmol) of3-phenyl-9H-carbazole, and 0.19 g (2.0 mmol) of sodium tert-butoxide.The atmosphere in the flask was replaced with nitrogen. Then, to thismixture were added 20 mL of toluene and 0.20 mL of a solution oftri(tert-butyl)phosphine (10 wt %) in hexane. This mixture was stirredto be degassed while the pressure was reduced. After that, 27 mg (0.047mmol) of bis(dibenzylideneacetone)palladium(0) was added to the mixture.

This mixture was stirred under a nitrogen stream at 110° C. for 2 hours.Then, this mixture was suction filtered through Celite (manufactured byWako Pure Chemical Industries, Ltd., Catalog No. 531-16855), alumina,and Florisil (manufactured by Wako Pure Chemical Industries, Ltd.,Catalog No. 540-00135). A solid obtained by concentration of theresulting filtrate was purified by silica gel column chromatography (thedeveloping solvent was a mixed solvent of a 5:1 ratio of hexane totoluene). The light yellow solid obtained was recrystallized with amixed solvent of toluene and hexane to give the desired compound as 0.44g of a light yellow powder in a yield of 81%.

As in Example of Production of CzPAP in Example 1, by a nuclear magneticresonance (NMR) method, this compound was confirmed to be3-phenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation:CzPAP) which was the desired compound.

Comparative Example 2 Synthesis of CzPAP by Second Known Method

In Comparative Example 2, an example will be described in which3-phenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation:CzPAP) represented by Structural Formula 1 is produced by the secondknown method which is a known production method, as described above.

[Step 1]

This step is a step of synthesizing9-(4-bromophenyl)-3-phenyl-9H-carbazole. The step is illustrated inReaction Formula (R2-1) and will be detailed hereinbelow.

In a 500 mL three neck flask were put 8.0 g (34 mmol) of1,4-dibromobenzene, 7.0 g (28 mmol) of 3-phenyl-9H-carbazole, and 0.27 g(1.0 mmol) of 18-crown-6-ether. This mixture was stirred while beingheated at about 130° C., so that 1,4-dibromobenzene was melted. Afterthat, to this mixture were added 3.0 mL of1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (DMPU), 9.5 g (69mmol) of potassium carbonate, and 0.20 g (1.0 mmol) of copper(I) iodide,followed by stirring at 170° C. for 3 hours. Then, this mixture wascooled to about 110° C. Next, 100 mL of toluene was added to thismixture, which was cooled to room temperature.

This mixture was suction filtered. The resulting filtrate was washedwith dilute hydrochloric acid three times, with a saturated aqueoussodium hydrogen carbonate solution three times, and with saturated brineonce. Then, the mixture was separated into an aqueous layer and anorganic layer. The organic layer was dried with magnesium sulfate, andthis mixture was gravity filtered. An oily substance obtained byconcentration of the resulting filtrate was purified by silica gelcolumn chromatography (the developing solvent was a mixed solvent of a7:1 ratio of hexane to toluene) to give a colorless oily substance. Thisoily substance was melted in a small amount of hexane. Methanol wasadded to this mixture, followed by irradiation with ultrasonic waves toprecipitate a white solid. This solid was collected by suctionfiltration to give the desired substance as 2.5 g of a white powder in ayield of 22%.

[Step 2]

This step is a step of synthesizing4-(3-phenyl-9H-carbazol-9-yl)phenylboronic acid. The step is illustratedin Reaction Formula (R2-2) and will be detailed hereinbelow.

In a 300 mL three neck flask was put 2.5 g (6.2 mmol) of9-(4-bromophenyl)-3-phenyl-9H-carbazole. The atmosphere in the flask wasreplaced with nitrogen. In this flask was put 100 mL of tetrahydrofuran(THF), and this solution was cooled to −80° C. To this solution wasadded 4.2 mL (7.0 mmol) of a solution of n-butyllithium (1.6 mol/L) inhexane by being dripped with a syringe. After completion of dripping,this solution was stirred at the same temperature for 1 hour. Then, 0.72mL (7.5 mmol) of trimethyl borate was added to this solution, and themixture was stirred for 2 hours while being returned to roomtemperature. After that, about 50 mL of dilute hydrochloric acid (1.0mol/L) was added to this solution, followed by stirring for 2 hours.

After being stirred, this mixture was separated into an aqueous layerand an organic layer. The aqueous layer was extracted with ethylacetate. The extract and the organic layer were combined and washed witha saturated aqueous sodium hydrogen carbonate solution and saturatedbrine. The organic layer was dried with magnesium sulfate, followed bygravity filtration of this mixture. The resulting filtrate wasconcentrated to give an oily substance. This oily substance was meltedin a small amount of chloroform. Hexane was added to this mixture,followed by irradiation with ultrasonic waves to precipitate a whitesolid. This solid was collected by suction filtration to give thedesired substance as 1.5 g of a white powder in a yield of 67%.

[Step 3]

This step is a step of synthesizing3-phenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation:CzPAP). The step is illustrated in Reaction Formula (R2-3) and will bedetailed hereinbelow.

In a 100 mL three neck flask were put 1.4 g (4.1 mmol) of9-bromo-10-phenylanthracene and 1.5 g (4.1 mmol) of4-(3-phenyl-9H-carbazol-9-yl)phenylboronic acid. The atmosphere in theflask was replaced with nitrogen. Then, to this mixture were added 50 mLof toluene and 5.0 mL of an aqueous potassium carbonate solution (2.0mol/L). The mixture was stirred to be degassed while the pressure wasreduced. To this mixture was added 0.24 g (0.20 mmol) oftetrakis(triphenylphosphine)palladium(0), and the mixture was stirredunder a nitrogen stream at 80° C. for 9 hours.

After being stirred, this mixture was separated into an aqueous layerand an organic layer. The aqueous layer was extracted with toluene. Theextract and the organic layer were combined and washed with saturatedbrine. The organic layer was dried with magnesium sulfate, followed bygravity filtration of this mixture. A solid obtained by concentration ofthe resulting filtrate was dissolved in about 10 mL of toluene. Thissolution was suction filtered through Celite (manufactured by Wako PureChemical Industries, Ltd., Catalog No. 531-16855), alumina, and Florisil(manufactured by Wako Pure Chemical Industries, Ltd., Catalog No.540-00135). An oily substance obtained by concentration of the resultingfiltrate was purified by silica gel column chromatography (thedeveloping solvent was a mixed solvent of a 5:1 ratio of hexane totoluene) to give a light yellow oily substance.

This oily substance was recrystallized with a mixed solvent of tolueneand hexane to give the desired substance as 1.9 g of a light yellowpowder in a yield of 83%. As in Example of Production of CzPAP, by anuclear magnetic resonance (NMR) method, this compound was confirmed tobe 3-phenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole(abbreviation: CzPAP) which was the desired compound.

Example 2 Example of Production of CzPAaNP

In Example 2, an example in which3-[4-(1-naphthyl)phenyl]-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole(abbreviation: CzPAaNP) represented by the above Structural Formula 2 isproduced will be described. The example is illustrated in ReactionFormula (E2) and will be detailed hereinbelow.

In a 200 mL three neck flask were put 2.5 g (4.4 mmol) of3-bromo-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole, 1.1 g (4.4 mmol)of 4-(1-naphthyl)phenylboronic acid, and 0.33 g (1.1 mmol) oftri(ortho-tolyl)phosphine. The atmosphere in the flask was replaced withnitrogen. To this mixture were added 5.0 mL of an aqueous potassiumcarbonate solution (2.0 mol/L), 60 mL of toluene, and 20 mL of ethanol.This mixture was stirred to be degassed while the pressure was reduced.To this mixture was added 49 mg (0.22 mmol) of palladium(II) acetate.This mixture was stirred under a nitrogen stream at 80° C. for 5 hours.

After being stirred, the mixture was separated into an aqueous layer andan organic layer. The aqueous layer was extracted with toluene. Theextract and the organic layer were combined and washed with saturatedbrine. Then, the organic layer was dried with magnesium sulfate,followed by gravity filtration of this mixture. An oily substanceobtained by concentration of the resulting filtrate was dissolved inabout 10 mL of toluene. This solution was suction filtered throughCelite (manufactured by Wako Pure Chemical Industries, Ltd., Catalog No.531-16855), alumina, and Florisil (manufactured by Wako Pure ChemicalIndustries, Ltd., Catalog No. 540-00135). An oily substance obtained byconcentration of the resulting filtrate was purified by silica gelcolumn chromatography (the developing solvent was a mixed solvent of a5:1 ratio of hexane to toluene) to give a light yellow oily substance.

This oily substance was recrystallized with a mixed solvent of tolueneand hexane to give the desired substance as 2.4 g of a light yellowpowder in a yield of 79%. Sublimation purification of 2.3 g of the lightyellow powder obtained was performed by a train sublimation method. Thelight yellow powder was heated at 340° C. with an argon flow rate of 4.0mL/min under reduced pressure. After the sublimation purification, 2.2 gof a light yellow solid which was the desired substance was obtained ina yield of 95%. By a nuclear magnetic resonance (NMR) method, thiscompound was confirmed to be3-[4-(1-naphthyl)phenyl]-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole(abbreviation: CzPAaNP) which was the desired compound.

The following are data of the ¹H NMR measurement of the compoundobtained: ¹H NMR (CDCl₃, 300 MHz): δ=7.37-7.67 (m, 17H), 7.70-7.80 (m,6H), 7.85-7.96 (m, 9H), 8.06 (d, J=8.1 Hz, 1H), 8.29 (d, J=7.8 Hz, 1H),8.52 (d, J=0.90 Hz, 1H)

In addition, FIGS. 18A and 18B show ¹H NMR charts. Note that FIG. 18B isa chart showing an enlarged part in the range of 7.2 ppm to 8.4 ppm inFIG. 18A.

Example 3 Example of Production of CzPAaN

In Example 3, an example in which3-(1-naphthyl)-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole(abbreviation: CzPAcN) represented by the above Structural Formula 4 isproduced will be described. The example is illustrated in ReactionFormula (E3) and will be detailed hereinbelow.

In a 200 mL three neck flask were put 2.8 g (4.9 mmol) of3-bromo-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole, 0.84 g (4.9mmol) of 1-naphthylboronic acid, and 0.36 g (1.2 mmol) oftri(ortho-tolyl)phosphine. The atmosphere in the flask was replaced withnitrogen. To this mixture were added 5.0 mL of an aqueous potassiumcarbonate solution (2.0 mol/L), 60 mL of toluene, and 20 mL of ethanol.This mixture was stirred to be degassed while the pressure was reduced.To this mixture was added 55 mg (0.24 mmol) of palladium(II) acetate.The resulting mixture was stirred under a nitrogen stream at 80° C. for4 hours. After being stirred, the mixture was separated into an aqueouslayer and an organic layer. The aqueous layer was extracted withtoluene. The extract and the organic layer were combined and washed withsaturated brine. The organic layer was dried with magnesium sulfate,followed by gravity filtration of this mixture.

An oily substance obtained by concentration of the resulting filtratewas dissolved in about 10 mL of toluene. This solution was suctionfiltered through Celite (manufactured by Wako Pure Chemical Industries,Ltd., Catalog No. 531-16855), alumina, and Florisil (manufactured byWako Pure Chemical Industries, Ltd., Catalog No. 540-00135). An oilysubstance obtained by concentration of the resulting filtrate waspurified by silica gel column chromatography (the developing solvent wasa mixed solvent of a 5:1 ratio of hexane to toluene) to give a lightyellow oily substance. This light yellow solid obtained wasrecrystallized with a mixed solvent of toluene and hexane to give thedesired substance as 1.8 g of a light yellow powder in a yield of 60%.

Sublimation purification of 1.8 g of the light yellow powder obtainedwas performed by a train sublimation method. The light yellow powder washeated at 320° C. with an argon flow rate of 4.0 mL/min under reducedpressure. After the sublimation purification, 1.7 g of a light yellowsolid which was the desired substance was obtained in a yield of 94%. Bya nuclear magnetic resonance (NMR) method, this compound was confirmedto be 3-(1-naphthyl)-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole(abbreviation: CzPActN).

The following are data of the ¹H NMR measurement of the compoundobtained: ¹H NMR (CDCl₃, 300 MHz): δ=7.34-7.67 (m, 16H), 7.72-7.81 (m,6H), 7.85-7.96 (m, 6H), 8.07 (d, J=8.4 Hz, 1H), 8.20 (d, J=7.8 Hz, 1H),8.32 (d, J=1.5 Hz, 1H)

In addition, FIGS. 19A and 19B show ¹H NMR charts. Note that FIG. 19B isa chart showing an enlarged part in the range of 7.0 ppm to 8.5 ppm inFIG. 19A.

Example 4 Example of Production of CzPAβN

In Example 3, an example in which3-(2-naphthyl)-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole(abbreviation: CzPAβN) represented by the above Structural Formula 5 isproduced will be described. The example is illustrated in ReactionFormula (E4) and will be detailed hereinbelow.

In a 100 mL three neck flask were put 1.0 g (1.7 mmol) of3-bromo-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole, 0.30 g (1.7mmol) of 2-naphthylboronic acid, and 0.13 g (0.42 mmol) oftri(ortho-tolyl)phosphine. The atmosphere in the flask was replaced withnitrogen. To this mixture were added 30 mL of toluene, 10 mL of ethanol,and 2.0 mL of an aqueous potassium carbonate solution (2.0 mol/L). Thismixture was stirred to be degassed while the pressure was reduced. Tothis mixture was added 19 mg (0.085 mmol) of palladium(II) acetate. Theresulting mixture was stirred under a nitrogen stream at 80° C. for 3hours.

After being stirred, the mixture was separated into an aqueous layer andan organic layer. The aqueous layer was extracted with toluene. Theextract and the organic layer were combined and washed with saturatedbrine. The organic layer was dried with magnesium sulfate, followed bygravity filtration of this mixture. An oily substance obtained byconcentration of the resulting filtrate was dissolved in about 10 mL oftoluene. This solution was suction filtered through Celite (manufacturedby Wako Pure Chemical Industries, Ltd., Catalog No. 531-16855), alumina,and Florisil (manufactured by Wako Pure Chemical Industries, Ltd.,Catalog No. 540-00135). An oily substance obtained by concentration ofthe resulting filtrate was purified by silica gel column chromatography(the developing solvent was a mixed solvent of a 5:1 ratio of hexane totoluene) to give a light yellow oily substance. This light yellow solidobtained was recrystallized with a mixed solvent of toluene and hexaneto give the desired substance as 0.73 g of a light yellow powder in ayield of 69%.

Sublimation purification of 0.71 g of the light yellow powder obtainedwas performed by a train sublimation method. The light yellow powder washeated at 310° C. with an argon flow rate of 4.0 mL/min under reducedpressure. After the sublimation purification, 0.64 g of a light yellowsolid which was the desired substance was obtained in a yield of 90%. Bya nuclear magnetic resonance (NMR) method, this compound was confirmedto be 3-(2-naphthyl)-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole(abbreviation: CzPAβN) which was the desired compound.

The following are data of the ¹H NMR measurement of the compoundobtained: ¹H NMR (CDCl₃, 300 MHz): δ=7.37-7.66 (m, 13H), 7.70-7.80 (m,6H), 7.85-8.00 (m, 9H), 8.20 (s, 1H), 8.30 (d, J=4.8 Hz, 1H), 8.54 (s,1H)

In addition, FIGS. 20A and 20B show ¹H NMR charts. Note that FIG. 20B isa chart showing an enlarged part in the range of 7.0 ppm to 9.0 ppm inFIG. 20A.

Example 5 Example of Production of CzPApB

In Example 5, an example in which3-(biphenyl-4-yl)-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole(abbreviation: CzPApB) represented by the above Structural Formula 6 isproduced will be described. The example is illustrated in ReactionFormula (E5) and will be detailed hereinbelow.

In a 300 mL three neck flask were put 3.0 g (5.2 mmol) of3-bromo-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole, 1.0 g (5.2 mmol)4-biphenylboronic acid, and 0.40 g (1.3 mmol) oftri(ortho-tolyl)phosphine. The atmosphere in the flask was replaced withnitrogen. To this mixture were added 60 mL of toluene, 20 mL of ethanol,and 5.0 mL of an aqueous potassium carbonate solution (2.0 mol/L). Thismixture was stirred to be degassed while the pressure was reduced. Tothis mixture was added 58 mg (0.26 mmol) of palladium(II) acetate. Thismixture was stirred under a nitrogen stream at 80° C. for 3 hours,whereby a light black solid was precipitated.

This mixture was cooled to room temperature. Then, the solidprecipitated was collected by suction filtration. The solid collectedwas dissolved in about 100 mL of toluene. This solution was suctionfiltered through Celite (manufactured by Wako Pure Chemical Industries,Ltd., Catalog No. 531-16855), alumina, and Florisil (manufactured byWako Pure Chemical Industries, Ltd., Catalog No. 540-00135). Theresulting filtrate was concentrated to give a light yellow powder. Thesolid obtained was recrystallized with toluene to give the desiredsubstance as 2.0 g of a light yellow powdered solid in a yield of 59%.

Sublimation purification of 1.8 g of the light yellow powder obtainedwas performed by a train sublimation method. The light yellow powder washeated at 320° C. with an argon flow rate of 4.0 mL/min under reducedpressure. After the sublimation purification, 1.5 g of a light yellowsolid which was the desired substance was obtained in a yield of 84%. Bya nuclear magnetic resonance (NMR) method, this compound was confirmedto be 3-(biphenyl-4-yl)-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole(abbreviation: CzPApB) which was the desired compound.

The following are data of the ¹H NMR measurement of the compoundobtained: ¹H NMR (CDCl₃, 300 MHz): δ=7.35-7.80 (m, 25H), 7.82-7.88 (m,6H), 8.27 (d, J=7.8 Hz, 1H), 8.47 (d, J=1.5 Hz, 1H)

In addition, FIGS. 21A and 21B show ¹H NMR charts. Note that FIG. 21B isa chart showing an enlarged part in the range of 7.0 ppm to 8.5 ppm inFIG. 21A.

Example 6 Example of Production of CzPAoB

In Example 6, an example in which3-(biphenyl-2-yl)-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole(abbreviation: CzPAoB) represented by Structural Formula 8 below isproduced will be described. The example is illustrated in ReactionFormula (E6) and will be detailed hereinbelow.

In a 300 mL three neck flask were put 3.0 g (5.2 mmol) of3-bromo-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole, 1.0 g (5.2 mmol)of 2-biphenylboronic acid, and 0.40 g (1.3 mmol) oftri(ortho-tolyl)phosphine. The atmosphere in the flask was replaced withnitrogen. To this mixture were added 60 mL of toluene, 20 mL of ethanol,and 5.0 mL of an aqueous potassium carbonate solution (2.0 mol/L). Thismixture was stirred to be degassed while the pressure was reduced. Tothis mixture was added 58 mg (0.26 mmol) of palladium(II) acetate.

This mixture was stirred under a nitrogen stream at 80° C. for 3 hours.After being stirred, the mixture was separated into an aqueous layer andan organic layer. The aqueous layer was extracted with toluene. Theextract and the organic layer were combined and washed with saturatedbrine. The organic layer was dried with magnesium sulfate, followed bygravity filtration of this mixture. An oily substance obtained byconcentration of the resulting filtrate was dissolved in about 10 mL oftoluene. This solution was suction filtered through Celite (manufacturedby Wako Pure Chemical Industries, Ltd., Catalog No. 531-16855), alumina,and Florisil (manufactured by Wako Pure Chemical Industries, Ltd.,Catalog No. 540-00135). An oily substance obtained by concentration ofthe resulting filtrate was purified by silica gel column chromatography(the developing solvent was a mixed solvent of a 5:1 ratio of hexane totoluene) to give a light yellow oily substance. This light yellow solidobtained was recrystallized with a mixed solvent of toluene and hexaneto give the desired substance as 2.0 g of a light yellow powder in ayield of 67%.

Sublimation purification of 2.0 g of the light yellow powder obtainedwas performed by a train sublimation method. The light yellow powder washeated at 280° C. with an argon flow rate of 4.0 mL/min under reducedpressure. After the sublimation purification, 1.9 g of a light yellowsolid which was the desired substance was obtained in a yield of 93%. Bya nuclear magnetic resonance (NMR) method, this compound was confirmedto be 3-(biphenyl-2-yl)-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole(abbreviation: CzPAoB) which was the desired compound.

The following are data of the ¹H NMR measurement of the compoundobtained: ¹H NMR (DMSO-d₆, 300 MHz): δ=7.14-7.27 (m, 6H), 7.33 (t, J=7.5Hz, 1H), 7.45-7.81 (m, 22H), 7.87 (d, J=8.1 Hz, 2H), 8.21 (d, J=9.0 Hz,2H)

In addition, FIGS. 22A and 22B show ¹H NMR charts. Note that FIG. 22B isa chart showing an enlarged part in the range of 7.0 ppm to 8.5 ppm inFIG. 22A.

Example 7 Example of Production of CzPAFL

In Example 7, an example in which3-(9,9-dimethylfluoren-2-yl)-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole(abbreviation: CzPAFL) represented by the above Structural Formula 15 isproduced will be described. The example is illustrated in ReactionFormula (E7) and will be detailed hereinbelow.

In a 100 mL three neck flask were put 0.80 g (1.4 mmol) of3-bromo-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole, 0.33 g (1.4mmol) of 9,9-dimethylfluorene-2-boronic acid, and 0.11 g (0.35 mmol) oftri(ortho-tolyl)phosphine. The atmosphere in the flask was replaced withnitrogen. To this mixture were added 2.0 mL of an aqueous potassiumcarbonate solution (2.0 mol/L), 30 mL of toluene, and 10 mL of ethanol.This mixture was stirred to be degassed while the pressure was reduced.

To this mixture was added 16 mg (0.070 mmol) of palladium(II) acetate.This mixture was stirred under a nitrogen stream at 80° C. for 4 hours,whereby a light black solid was precipitated. This mixture was cooled toroom temperature. Then, the solid precipitated was collected by suctionfiltration. The solid collected was dissolved in about 50 mL of toluene.The mixture was added to the filtrate resulting from the above suctionfiltration. This mixture was separated into an aqueous layer and anorganic layer. The aqueous layer was extracted with toluene. The extractand the organic layer were combined and washed with saturated brine. Theorganic layer was dried with magnesium sulfate, followed by gravityfiltration of this mixture.

A solid obtained by concentration of the resulting filtrate wasdissolved in about 50 mL of toluene. This solution was suction filteredthrough Celite (manufactured by Wako Pure Chemical Industries, Ltd.,Catalog No. 531-16855), alumina, and Florisil (manufactured by Wako PureChemical Industries, Ltd., Catalog No. 540-00135). A solid obtained byconcentration of the resulting filtrate was purified by silica gelcolumn chromatography (the developing solvent was a mixed solvent of a5:1 ratio of hexane to toluene) to give a light yellow solid. This solidwas recrystallized with a mixed solvent of toluene and hexane to givethe desired substance as 0.57 g of a light yellow powder in a yield of54%.

Sublimation purification of 0.54 g of the light yellow powder obtainedwas performed by a train sublimation method. The light yellow powder washeated at 330° C. with an argon flow rate of 4.0 mL/min under reducedpressure. After the sublimation purification, 0.50 g of a light yellowsolid which was the desired substance was obtained in a yield of 93%. Bya nuclear magnetic resonance (NMR) method, this compound was confirmedto be3-(9,9-dimethylfluoren-2-yl)-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole(abbreviation: CzPAFL) which was the desired compound.

The following are data of the ¹H NMR measurement of the compoundobtained: ¹H NMR (CDCl₃, 300 MHz): δ=1.61 (s, 6H), 7.34-7.54 (m, 11H),7.57-7.66 (m, 3H), 7.70-7.81 (m, 10H), 7.84-7.89 (m, 5H), 8.30 (d, J=7.5Hz, 1H), 8.47 (s, 1H)

In addition, FIGS. 23A and 23B show ¹H NMR charts. Note that FIG. 23B isa chart showing an enlarged part in the range of 7.1 ppm to 8.6 ppm inFIG. 23A.

Example of Production of Light-Emitting Elements

In this example of the production, an example in which light-emittingelements are formed using carbazole derivatives produced by a productionmethod of Embodiment 1 will be described with reference to FIG. 24. Inaddition, Table 1 shows an element structure of each of Light-EmittingElements 1 and 2, in which all the mixture ratios are weight ratios.

TABLE 1 Light-Emitting Light-Emitting Element 1 Element 2 FirstElectrode 2102 ITSO 110 nm ITSO 110 nm First Layer 2103 NPB:MoOxNPB:MoOx (=4:1) 50 nm (=4:1) 50 nm Second Layer 2104 NPB 10 nm NPB 10 nmThird Layer 2105 CzPAP:PCBAPA CzPAP:2PCAPA (=1:0.1) 30 nm (=1:0.05) 30nm Fourth Layer 2106 Alq 10 nm Alq:DPQd (=1:0.005) 10 nm Bphen 20 nmBphen 30 nm Fifth Layer 2107 LiF 1 nm LiF 1 nm Second Electrode 2108 Al200 nm Al 200 nm

Hereinafter, a method of forming Light-Emitting Elements 1 and 2according to this example will be described in turn. First, an exampleof formation of Light-Emitting Element 1 will be described. ForLight-Emitting Element 1, indium tin oxide containing silicon oxide(ITSO) was deposited on a glass substrate 2101 by a sputtering method,whereby a first electrode 2102 was formed. Note that the thickness ofthe first electrode was 110 nm and the area of the electrode was set to2 mm×2 mm.

Next, the glass substrate provided with the first electrode was fixed toa substrate holder provided in a vacuum evaporation apparatus such thatthe surface on which the first electrode was formed faced downward.After the pressure was reduced to approximately 10⁻⁴ Pa,4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB) andmolybdenum(VI) oxide were co-evaporated on the first electrode 2102,whereby a layer including a composite material of an organic compoundand an inorganic compound was formed as a first layer 2103. Thethickness of the first layer was set to 50 nm, and the weight ratio ofNPB to molybdenum(VI) oxide was adjusted to be 4:1 (═NPB:molybdenumoxide). Note that the co-evaporation method refers to an evaporationmethod by which evaporation of a plurality of materials is conductedfrom a plurality of evaporation sources at the same time in onetreatment chamber. Successively, NPB was evaporated to form a10-nm-thick film as a second layer 2104 as a hole-transport layer.

Next, on the second layer 2104, CzPAP produced in Example 1 and4-(10-phenyl-9-anthryl)-4′-(9-phenyl-9H-carbazol-3-yl)triphenylamine(abbreviation: PCBAPA) were co-evaporated with the weight ratio of CzPAPto PCBAPA being 1:0.1, whereby a third layer 2105 was formed as alight-emitting layer. The thickness of the light-emitting layer was setto 30 nm.

Next, on the third layer 2105, a 10-nm-thick film of Alq and a20-nm-thick film of Bphen were formed by evaporation and stacked,whereby a fourth layer 2106 was formed as an electron-transport layer.Further, lithium fluoride (LiF) was evaporated on the fourth layer 2106to a thickness of 1 nm, whereby a fifth layer 2107 was formed as anelectron-inject layer. Lastly, a 200-nm-thick film of aluminum wasformed as a second electrode 2108 which serves as a cathode. Thus,Light-Emitting Element 1 of this example was completed.

Next, an example of formation of Light-Emitting Element 2 will bedescribed. Light-Emitting Element 2 was formed in a manner similar tothat of Light-Emitting Element 1 except the third layer 2105 and thefourth layer 2106. For Light-Emitting Element 2, on the second layer2104, CzPAP produced in Example 1 and9,10-diphenyl-2-[N-phenyl-N-(9-phenyl-9H-carbazol-3-yl)amino]anthracene(abbreviation: 2PCAPA) were co-evaporated with the weight ratio of CzPAPto 2PCAPA being 1:0.05, whereby the third layer 2105 was formed as alight-emitting layer. The thickness of the third layer was set to 30 nm.

Next, on the third layer 2105, a 10-nm-thick film formed byco-evaporation of Alq and N,N′-diphenylquinacridone (abbreviation: DPQd)with the weight ratio of Alq to DPQd being 1:0.005 and a 30-nm-thickfilm formed by evaporation of Bphen were stacked, whereby the fourthlayer 2106 was formed as an electron-transport layer. Thus,Light-Emitting Element 2 of this example was completed. Note that in allof the above evaporation steps, a resistance heating method was adopted.In addition, Structural Formulae of NPB, PCBAPA, 2PCAPA, DPQd, Alq, andBphen are illustrated below.

The thus obtained Light-Emitting Elements 1 and 2 were sealed in a glovebox containing a nitrogen atmosphere so as not to be exposed to air.Then, operation characteristics of Light-Emitting Elements 1 and 2 weremeasured. Note that the measurement was carried out at room temperature(in the atmosphere kept at 25° C.).

FIG. 25 shows current density vs. luminance characteristics ofLight-Emitting Element 1. In FIG. 25, the horizontal axis representscurrent density (mA/cm²) and the vertical axis represents luminance(cd/m²). FIG. 26 shows voltage vs. luminance characteristics ofLight-Emitting Element 1. In FIG. 26, the horizontal axis representsapplied voltage (V) and the vertical axis represents luminance (cd/m²).FIG. 27 shows luminance vs. current efficiency characteristics ofLight-Emitting Element 1. In FIG. 27, the horizontal axis representsluminance (cd/m²) and the vertical axis represents current efficiency(cd/A). FIG. 28 shows an emission spectrum of Light-Emitting Element 1at a current of 1 mA. FIG. 28 indicates that Light-Emitting Element 1exhibits light emission from PCBAPA which is a blue light-emittingmaterial.

Light-Emitting Element 1 exhibited excellent blue light emission wherethe CIE chromaticity coordinates were (x=0.16, y=0.20) when theluminance was 1080 cd/m². In addition, the current efficiency andexternal quantum efficiency at a luminance of 1080 cd/m² were 5.7 cd/Aand 3.9% respectively. Further, the voltage, current density, and powerefficiency at a luminance of 1080 cd/m² were 4.4 V, 18.9 mA/cm², and 4.1μm/W, respectively.

FIG. 29 shows current density vs. luminance characteristics ofLight-Emitting Element 2. In FIG. 29 the horizontal axis representscurrent density (mA/cm²) and the vertical axis represents luminance(cd/m²). FIG. 30 shows voltage vs. luminance characteristics ofLight-Emitting Element 2. In FIG. 30, the horizontal axis representsapplied voltage (V) and the vertical axis represents luminance (cd/m²).FIG. 31 shows luminance vs. current efficiency characteristics ofLight-Emitting Element 2. In FIG. 31, the horizontal axis representsluminance (cd/m²) and the vertical axis represents current efficiency(cd/A). FIG. 32 shows an emission spectrum of Light-Emitting Element 2at a current of 1 mA. FIG. 32 indicates that Light-Emitting Element 2exhibits light emission from 2PCAPA which is a green light-emittingmaterial.

Light-Emitting Element 2 exhibited excellent green light emission wherethe CIE chromaticity coordinates were (x=0.29, y=0.61) when theluminance was 5520 cd/m². In addition, the current efficiency at aluminance of 5520 cd/m² were 13 cd/A. Further, the voltage, currentdensity, and power efficiency at a luminance of 5520 cd/m² were 5.8 V,42.6 mA/cm², and 7.0 lm/W, respectively.

Further, reliability testing of Light-Emitting Elements 1 and 2 whichwere formed was carried out as follows. For Light-Emitting Element 1,the luminance was measured after every certain period of time passes,while the same amount of current as that flowing through Light-EmittingElement 1 when light emission with a luminance of 1000 cd/m² wasobtained in the initial state was continuously made flow. Also forLight-Emitting Element 2, the luminance was measured after every certainperiod of time passes, while the same amount of current as that flowingthrough Light-Emitting Element 2 when light emission with a luminance of5000 cd/m² was obtained in the initial state was continuously made flow.

FIG. 33 shows results obtained by the reliability testing ofLight-Emitting Element 1, and FIG. 34 shows results obtained by thereliability testing of Light-Emitting Element 2. FIG. 33 and FIG. 34each show a change in luminance over time. Note that in FIG. 33 and FIG.34, the horizontal axis represents current flow time (hour) and thevertical axis represents the proportion of luminance with respect to theinitial luminance at each time, that is, normalized luminance (%). Ascan be seen from FIG. 33, Light-Emitting Element 1 maintains 80% of theinitial luminance even after 430 hours; thus, Light-Emitting Element 1is found to have long lifetime in which luminance does not easilydeteriorate over time. Further, as can be seen from FIG. 34,Light-Emitting Element 2 maintains 82% of the initial luminance evenafter 570 hours; thus, Light-Emitting Element 2 is found to have longlifetime in which luminance does not easily deteriorate over time.

As described above, Light-Emitting Elements 1 and 2 which were highlyreliable were obtained. According to this example, it was confirmed thatthe light-emitting elements according to the embodiment of the presentinvention each have the characteristics as a light-emitting element andfunction sufficiently. Further, from the results of the reliabilitytesting, it is understood that a highly reliable light-emitting elementin which a short circuit due to defects of the film or the like is notcaused even if the element is continuously made to emit light can beobtained.

Example of Production of Chemical Substances Used in the Example ofProduction of Light-Emitting Elements

A substance used in Example of Production of Light-Emitting Element 1,4-(10-phenyl-9-anthryl)-4′-(9-phenyl-9H-carbazol-3-yl)triphenylamine(abbreviation: PCBAPA), is a novel substance and has a structure below.Hereinafter, a method for producing this substance will be described asan example of production of the chemical substances used in Example ofProduction of Light-Emitting Elements. The production process includesthree reaction steps, and each step will be specifically describedbelow.

First Step is a step of synthesizing 9-phenyl-9H-carbazole-3-boronicacid and illustrated in the following Reaction Formula (P1).

In this step, first, in a 500 mL three neck flask was put 10 g (31 mmol)of 3-bromo-9-phenyl-9H-carbazole. The atmosphere in the flask wasreplaced with nitrogen. In the flask was put 150 mL of tetrahydrofuran(THF), and 3-bromo-9-phenyl-9H-carbazole was dissolved therein. Thissolution was cooled to −80° C. To this solution was added 20 mL (32mmol) of a solution of n-butyllithium (1.58 mol/L) in hexane by beingdripped with a syringe. After that, the solution was stirred at the sametemperature for 1 hour.

After the solution was stirred, 3.8 mL (34 mmol) of trimethyl borate wasadded to this solution. The solution was stirred for about 15 hourswhile the temperature of the solution was being returned to roomtemperature. Then, about 150 mL (1.0 mol/L) of dilute hydrochloric acidwas added to this solution, followed by stirring for 1 hour. After beingstirred, this mixture was separated into an aqueous layer and an organiclayer. The aqueous layer was extracted with ethyl acetate. The extractand the organic layer were combined and washed with a saturated aqueoussodium hydrogen carbonate solution. The organic layer was dried withmagnesium sulfate, and then this mixture was gravity filtered. Theresulting filtrate was concentrated to give an oily light brownsubstance. This oily substance was dried under reduced pressure to givethe desired substance as 7.5 g of a light brown solid in a yield of 86%.

[Second Step]

Second Step is a step of synthesizing4-(9-phenyl-9H-carbazol-3-yl)diphenylamine (abbreviation: PCBA) andillustrated in the following Reaction Formula (P2).

In this step, first, in a 500 mL three neck flask were put 6.5 g (26mmol) of 4-bromo-diphenylamine, 7.5 g (26 mmol) of9-phenyl-9H-carbazole-3-boronic acid, and 400 mg (1.3 mmol) oftri(ortho-tolyl)phosphine. The atmosphere in the flask was replaced withnitrogen. To this mixture were added 100 mL of toluene, 50 mL ofethanol, and 14 mL of an aqueous potassium carbonate solution (2.0mol/L). Under reduced pressure, this mixture was degassed while beingstirred. After that, 67 mg (30 mmol) of palladium(II) acetate was addedto the mixture.

This mixture was refluxed for 10 hours at 100° C. After that, thismixture was separated into an aqueous layer and an organic layer. Theaqueous layer was extracted with toluene. The extract and the organiclayer were combined and washed with saturated brine. The organic layerwas dried with magnesium sulfate, followed by gravity filtration of thismixture. The resulting filtrate was concentrated to give an oily lightbrown substance. This oily substance was purified by silica gel columnchromatography (the developing solvent was a mixed solvent of a 4:6ratio of hexane to toluene). A white solid obtained after thepurification was recrystallized with a mixed solvent of dichloromethaneand hexane to give the desired substance as 4.9 g of a white solid in ayield of 45%. The solid obtained by the above Second Step was measuredby a nuclear magnetic resonance (NMR) method.

The measurement data obtained by ¹H NMR are described below. Themeasurement results indicate that PCBA, which was a source material ofthe synthesis of PCBAPA, was obtained. ¹H NMR (DMSO-d₆, 300 MHz):δ=6.81-6.86 (m, 1H), 7.12 (dd, J₁=0.9 Hz, J₂=8.7 Hz, 2H), 7.19 (d, J=8.7Hz, 2H), 7.23-7.32 (m, 3H), 7.37-7.4 7(m, 3H), 7.51-7.57 (m, 1H),7.61-7.73 (m, 7H) 8.28 (s, 1H), 8.33 (d, J=7.2 Hz, 1H), 8.50 (d, J=1.5Hz, 1H)

[Third Step]

Third Step is a step of synthesizing PCBAPA and illustrated in thefollowing Reaction Formula (P3).

In this step, first, in a 300 mL three neck flask were put 7.8 g (12mmol) of 9-(4-bromophenyl)-10-phenylanthracene, 4.8 g (12 mmol) of PCBA,and 5.2 g (52 mmol) of sodium tert-butoxide. The atmosphere in the flaskwas replaced with nitrogen. To the mixture were added 60 mL of tolueneand 0.30 mL of a solution of tri(tert-butyl)phosphine (10 wt %) inhexane. Under reduced pressure, this mixture was degassed while beingstirred. After that, 136 mg (0.24 mmol) ofbis(dibenzylideneacetone)palladium(0) was added to the mixture.

The mixture was stirred at 100° C. for 3 hours. Then, about 50 mL oftoluene was added to this mixture, followed by suction filtrationthrough Celite (manufactured by Wako Pure Chemical Industries, Ltd.,Catalog No. 531-16855), alumina, and Florisil (manufactured by Wako PureChemical Industries, Ltd., Catalog No. 540-00135). The resultingfiltrate was concentrated to give a yellow solid. This solid wasrecrystallized with a mixed solvent of toluene and hexane to give thedesired substance as 6.6 g of a light yellow powder of PCBAPA in a yieldof 75%.

The solid obtained by the above Third Step was measured by a nuclearmagnetic resonance (NMR) method. The measurement data obtained by ¹H NMRare described below. The measurement results indicate that PCBAPA wasobtained. ¹H NMR (CDCl₃, 300 MHz): δ=7.09-7.14 (m, 1H), 7.28-7.72 (m,33H), 7.88 (d, J=8.4 Hz, 2H), 8.19 (d, J=7.2 Hz, 1H), 8.37 (d, J=1.5 Hz,1H)

This application is based on Japanese Patent Application serial no.2008-240299 filed with Japan Patent Office on Sep. 19, 2008, the entirecontents of which are hereby incorporated by reference.

1. A carbazole derivative represented by Compound (2),

wherein X⁷ represents any one of halogen, boronic acid, an organoboroncompound, an organotin compound, trifluoromethanesulfonate, a Grignardreagent, an organic mercury compound, thiocyanate, an organozinccompound, an organoaluminum compound, and an organozirconium compound.2. The carbazole derivative according to claim 1, wherein X⁷ representshalogen or trifluoromethanesulfonate.
 3. The carbazole derivativeaccording to claim 1, wherein X⁷ represents boronic acid or anorganoboron compound.
 4. A carbazole derivative represented by Compound(M1),

wherein X¹ represents halogen.
 5. The carbazole derivative according toclaim 4, wherein X¹ represents iodine or bromine.
 6. A method forproducing a carbazole derivative represented by Compound (M1)comprising: halogenating 9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole,

wherein X¹ represents halogen.
 7. The method according to claim 6,wherein X¹ represents iodine or bromine.
 8. The method according toclaim 6, wherein the halogenation is bromination, and wherein thebromination is carried out using a brominating agent.
 9. The methodaccording to claim 8, wherein the brominating agent includes bromine orN-bromosuccinimide.
 10. The method according to claim 8, wherein asolvent for the bromination is chloroform or carbon tetrachloride. 11.The method according to claim 8, wherein a solvent for the brominationis one selected from the group consisting of ethyl acetate,tetrahydrofuran, dimethylformamide, acetic acid, and water.
 12. Themethod according to claim 6, wherein the halogenation is iodination, andwherein the iodination is carried out using a iodinating agent.
 13. Themethod according to claim 12, wherein the iodinating agent is one ofselected from the group consisting of N-iodosuccinimide,1,3-diiodo-5,5-dimethylimidazolidine-2,4-dione,2,4,6,8-tetraiodo-2,4,6,8-tetraazabicyclo[3,3,0]octane-3,7-dione, and2-iodo-2,4,6,8-tetraazabicyclo[3,3,0]octane-3,7-dione.
 14. The methodaccording to claim 12, wherein a solvent for the iodination is at leastone selected from the group consisting of aromatic hydrocarbon, ether,saturated hydrocarbon, halogen, nitrile, ester, acetic acid, and water.15-18. (canceled)